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1.
Hong Xue 《Journal of molecular evolution》1998,47(3):323-333
The gene superfamily of ligand-gated ion channel (LGIC) receptors is composed of members of excitatory LGIC receptors (ELGIC)
and inhibitory LGIC receptors (ILGIC), all using amino acids as ligands. The ILGICs, including GABAA, Gly, and GluCl receptors, conduct Cl− when the ligand is bound. To evaluate the phylogenetic relationships among ILGIC members, 90 protein sequences were analyzed
by both maximum-parsimony and distance matrix-based methods. The strength of the resulting phylogenetic trees was evaluated
by means of bootstrap. Four major phylogenetic branches are recognized. Branch I, called BZ, for the majority of the members
are known to be related to benzodiazepine binding, is subdivided into IA, composed of all GABAA receptor α subunits, and IB, composed of the γ and ε subunits, which are shown to be tightly linked. Branch II, named NB
for non–benzodiazepine binding, and consisting of GABAA receptor β, δ, π, and ρ subunits, is further subdivided into IIA, containing β subunits; IIB, containing δ, and π subunits;
and IIC, containing ρ subunits. Branch IIIA, composed of vertebrate Gly receptors, is loosely clustered with Branch IIIB,
composed of invertebrate GluCl receptors, to form Branch III, which is designated NA for being non–GABA responsive. Branch
IV is called UD for being undefined in specificity. The existence of primitive forms of GABAA receptor non-β subunits in invertebrates is first suggested by the present analysis, and the identities of sequences p25123
from Drosophila melanogaster, s34469 from Lymnaea stagnalis, and u14635 and p41849 from C. aenorhabditis elegans are determined to be different from their previously given annotations. The proposed branching classification of ILGICs provides
a phylogenetic map, based on protein sequences, for tracing the evolutionary pathways of ILGIC receptor subunits and determining
the identities of newly discovered subunits on the basis of their protein sequences.
Received: 15 April 1997 / Accepted: 11 March 1998 相似文献
2.
Surfactant protein A (SP-A) functions in homeostasis of lung surfactant and in innate immunity. SP-A is secreted by the fetal lung into amniotic fluid. Additionally it has been detected in gestational tissues. We propose that SP-A influences intrauterine inflammation that is commonly associated with preterm birth, the main underlying cause of neonatal mortality and morbidity. We used our previously established mouse model of LPS-induced preterm birth of live-born pups to investigate the role of SP-A in preterm birth. Mice overexpressing rat SP-A (rSP-A) under the control of human SP-C promoter were used. Cytokine concentrations in maternal and fetal serum and in amniotic fluid and mRNA levels of several inflammatory mediators in lungs and in intrauterine tissues were quantified using Cytometric Bead Array and RNase Protection Assay, respectively. Higher levels of SP-A mRNA were observed in fetal lungs and intrauterine tissues of rSP-A mice compared with wild-type. Using Western blot we detected excess of SP-A protein in fetal lung and in amniotic fluid of rSP-A animals. Despite some differences in the basal levels of TNF-α and IL-10 between rSP-A and wild-type animals, there were no differences in the duration of pregnancy. However, the levels of TNF-α, IL-10 and some other inflammatory mediators in intrauterine tissues and in amniotic fluid differed significantly between the mouse lines after maternal LPS given at 17 dpc. We conclude that SP-A modulates the levels of intrauterine inflammatory mediators involved in preterm birth and may contribute to inflammatory processes related to spontaneous preterm labor. 相似文献
3.
4.
Insect vitellogenin and yolk protein receptors (VgR/YPR) are newly discovered members of the low-density lipoprotein receptor
(LDLR) family, which is characterized by a highly conserved arrangement of repetitive modular elements homologous to functionally
unrelated proteins. The insect VgR/YPRs are unique in having two clusters of complement-type cysteine-rich (class A) repeats
or modules, with five modules in the first cluster and seven in the second cluster, unlike classical LDLRs which have a single
seven-module cluster, vertebrate VgRs and very low density lipoprotein receptors (VLDLR) which have a single eight-module
cluster, and LDLR-related proteins (LRPs) and megalins which have four clusters of 2–7, 8, 10, and 11 modules. Alignment of
clusters across subfamilies by conventional alignment programs is problematic because of the repetitive nature of the component
modules which may have undergone rearrangements, duplications, and deletions during evolution. To circumvent this problem,
we ``fingerprinted' each class A module in the different clusters by identifying those amino acids that are both relatively
conserved and relatively unique within the cluster. Intercluster reciprocal comparisons of fingerprints and aligned sequences
allowed us to distinguish four cohorts of modules reflecting shared recent ancestry. All but two of the 57 modules examined
could be assigned to one of these four cohorts designated A, B, C, and D. Alignment of clusters based on modular cohorts revealed
that all clusters are derived from a single primordial cluster of at least seven modules with a consensus arrangement of CDCADBC.
All extant clusters examined are consistent with this consensus, though none matches it perfectly. This analysis also revealed
that the eight-module clusters in vertebrate VgRs, insect VgR/YPRs, and LRP/megalins are not directly homologous with one
another. Assignment of modules to cohorts permitted us to properly align 32 class A clusters from all four LDLR subfamilies
for phylogenetic analysis. The results revealed that smaller one-cluster and two-cluster members of the family did not originate
from the breakup of a large two-cluster or four-cluster receptor. Similarly, the LRP/megalins did not arise from the duplication
of a two-cluster insect VgR/YPR-like progenitor. Rather, it appears that the multicluster receptors were independently constructed
from the same single-cluster ancestor.
Received: 16 January 1997 / Accepted: 21 August 1997 相似文献
5.
Christine P. Piotte Airlie K. Hunter Craig J. Marshall Murray R. Grigor 《Journal of molecular evolution》1998,46(3):361-369
Three proteins have been identified in the milk of the common brush tail possum, Trichosurus vulpecula that from sequence analysis are members of the lipocalin family. They include β-lactoglobulin, which appears to have two
forms; a homologue to the late-lactation protein found in tammar, Macropus eugenii; milk; and a novel protein termed trichosurin. Whereas β-lactoglobulin and trichosurin are both expressed throughout lactation, the late-lactation protein is not detected
in samples taken before days 100–110 of lactation. The cDNAs encoding each of these proteins have been isolated from cDNA
libraries prepared using possum mammary mRNA and sequenced. Phylogenetic analysis showed that the T. vulpeculaβ-lactoglobulin, along with two other macropod β-lactoglobulins, forms a subclass of β-lactoglobulins distinct from those
for eutherian mammals; both marsupial late-lactation proteins appear to have similarities to a family of odorant-binding proteins,
whereas trichosurin has similarities to the major urinary proteins of rodents.
Received: 28 October 1996 / Accepted: 19 May 1997 相似文献
6.
7.
Quintero OA Korfhagen TR Wright JR 《American journal of physiology. Lung cellular and molecular physiology》2002,283(1):L76-L85
Previous in vitro studies have suggested that surfactant protein A (SP-A) may play a role in pulmonary surfactant homeostasis by mediating surfactant secretion and clearance. However, mice made deficient in SP-A [SP-A (-/-) animals] have relatively normal levels of surfactant compared with wild-type SP-A (+/+) animals. We hypothesize that SP-A may play a role in surfactant homeostasis after acute lung injury. Bacterial lipopolysaccharide was instilled into the lungs of SP-A (-/-) mice and SP-A (+/+) mice to induce injury. Surfactant phospholipid levels were increased 1.6-fold in injured SP-A (-/-) animals, although injury did not alter [3H]choline or [14C]palmitate incorporation into dipalmitoylphosphatidylcholine (DPPC), suggesting no change in surfactant synthesis/secretion 12 h after injury. Clearance of [3H]DPPC from the lungs of injured SP-A (-/-) animals was decreased by approximately 40%. Instillation of 50 microg of exogenous SP-A rescued both the clearance defect and the increased phospholipid defect in injured SP-A (-/-) animals, suggesting that SP-A may play a role in regulating clearance of surfactant phospholipids after acute lung injury. 相似文献
8.
We have compared all available deduced protein sequences of the ErbB family of receptors and their ligands. Analysis of the
aligned sequences of the receptors indicates that there are some differences in the receptors that are specific to invertebrates.
In addition, comparison of the vertebrate ErbB receptors suggest that a gene duplication event generated two ancestral receptors,
the ErbB3/ErbB4 precursor and the ErbB1/ErbB2 precursor. Subsequent gene duplications of these precursors generated the four
receptors present in mammals. Analysis of the sequences for the known ligands of the ErbB receptors suggests that the vertebrate
ligands segregate into the ErbB1 ligands and the ErbB3/ErbB4 ligands, paralleling the evolution of the receptors; however,
it is difficult to ascertain any correlation between the invertebrate and the vertebrate ligands. Even though ErbB3 is kinase-impaired,
there is significant conservation of the kinase domain within the vertebrate lineage (human, rat, and F. rubripes), suggesting some function for this domain other than kinase activity, such as mediating protein–protein interactions that
are involved in receptor dimerization and/or activation of the kinase domain of the heterodimerization partner. To date, no
ligand for ErbB2 has been identified, and comparison of the extracellular domains of ErbB2 reveals two regions that are not
conserved across the mammalian species. These two regions of divergence align with sequences in ErbB1 that have been shown
to be proximal to the amino-terminus and to the carboxyl-terminal region, respectively, of bound EGF. Further, one of these
regions contains an insertion, relative to the other members of the mammalian ErbB family, which might affect the ligand binding
site and provide a structural basis for this receptor's apparent inability to bind ligand independently.
Received: 8 September 1999 / Accepted: 17 January 2000 相似文献
9.
The aldo-keto reductase enzymes comprise a functionally diverse gene family which catalyze the NADPH-dependant reduction
of a variety of carbonyl compounds. The protein sequences of 45 members of this family were aligned and phylogenetic trees
were deduced from this alignment using the neighbor-joining and Fitch algorithms. The branching order of these trees indicates
that the vertebrate enzymes cluster in three groups, which have a monophyletic origin distinct from the bacterial, plant,
and invertebrate enzymes. A high level of conservation was observed between the vertebrate hydroxysteroid dehydrogenase enzymes,
prostaglandin F synthase, and ρ-crystallin of Xenopus laevis. We infer from the phylogenetic analysis that prostaglandin F synthase may represent a recent recruit to the eicosanoid biosynthetic
pathway from the hydroxysteroid dehydrogenase pathway and furthermore that, in the context of gene recruitment, Xenopus laevisρ-crystallin may represent a shared gene.
Received: 26 August 1996 / Accepted: 5 June 1997 相似文献
10.
Peter E.M. Gibbs Werner F. Witke Achilles Dugaiczyk 《Journal of molecular evolution》1998,46(5):552-561
The serum albumin gene family is composed of four members that have arisen by a series of duplications from a common ancestor.
From sequence differences between members of the gene family, we infer that a gene duplication some 580 Myr ago gave rise
to the vitamin D–binding protein (DBP) gene and a second lineage, which reduplicated about 295 Myr ago to give the albumin
(ALB) gene and a common precursor to α-fetoprotein (AFP) and α-albumin (ALF). This precursor itself duplicated about 250 Myr
ago, giving rise to the youngest family members, AFP and ALF. It should be possible to correlate these dates with the phylogenetic
distribution of members of the gene family among different species. All four genes are found in mammals, but AFP and ALF are
not found in amphibia, which diverged from reptiles about 360 Myr ago, before the divergence of the AFP-ALF progenitor from
albumin.
Although individual family members display an approximate clock-like evolution, there are significant deviations—the rates
of divergence for AFP differ by a factor of 7, the rates for ALB differ by a factor of 2.1. Since the progenitor of this gene
family itself arose by triplication of a smaller gene, the rates of evolution of individual domains were also calculated and
were shown to vary within and between family members. The great variation in the rates of the molecular clock raises questions
concerning whether it can be used to infer evolutionary time from contemporary sequence differences.
Received: 28 February 1995 / Accepted: 6 October 1997 相似文献
11.
Hughes AL 《Journal of molecular evolution》1999,48(5):565-576
It has been proposed that two rounds of duplication of the entire genome (polyploidization) occurred early in vertebrate
history (the 2R hypothesis); and the observation that certain gene families important in regulating development have four
members in vertebrates, as opposed to one in Drosophila, has been adduced as evidence in support of this hypothesis. However, such a pattern of relationship can be taken as support
of the 2R hypothesis only if (1) the four vertebrate genes can be shown to have diverged after the origin of vertebrates,
and (2) the phylogeny of the four vertebrate genes (A–D) exhibits a topology of the form (AB) (CD), rather than (A) (BCD).
In order to test the 2R hypothesis, I constructed phylogenies for nine protein families important in development. Only one
showed a topology of the form (AB) (CD), and that received weak statistical support. In contrast, four phylogenies showed
topologies of the form (A) (BCD) with statistically significant support. Furthermore, in two cases there was significant support
for duplication of the vertebrate genes prior to the divergence of deuterostomes and protostomes: in one case there was significant
support for duplication of the vertebrate genes at least prior to the divergence of vertebrates and urochordates, and in one
case there was weak support for duplication of the vertebrate genes prior to the divergence of deuterostomes and protostomes.
Taken together with other recently published phylogenies of developmentally important genes, these results provide strong
evidence against the 2R hypothesis.
Received: 22 December 1997 / Accepted: 5 October 1998 相似文献
12.
Evolution of the Integrin α and β Protein Families 总被引:4,自引:0,他引:4
Hughes AL 《Journal of molecular evolution》2001,52(1):63-72
A phylogenetic analysis of vertebrate and invertebrate α integrins supported the hypothesis that two major families of vertebrate
α integrins originated prior to the divergence of deuterostomes and protostomes. These two families include, respectively,
the αPS1 and αPS2 integrins of Drosophila melanogaster, and each family has duplicated repeatedly in vertebrates but not in Drosophila. In contrast, a third family (including αPS3) has duplicated in Drosophila but is absent from vertebrates. Vertebrate αPS1 and αPS2 family members are found on human chromosomes 2, 12, and 17. Linkage
of these family members may have been conserved since prior to the origin of vertebrates, and the two genes duplicated simultaneously.
A phylogenetic analysis of β integrins did not clearly resolve whether vertebrate β integrin genes duplicated prior to the
origin of vertebrates, although it suggested that at least the gene encoding vertebrate β4 may have done so. In general, the
phylogeny of neither α nor β integrins showed a close correspondence with patterns of α–β heterodimer formation or other functional
characteristics. One major exception to this trend involved αL, αM, αX, and αD, a monophyletic group of immune cell-expressed
α integrins, which share a number of common functional characteristics and have evolved in coordinated fashion with their
β integrin partners.
Received: 22 June 2000 / Accepted: 11 September 2000 相似文献
13.
Ivan Laprevotte Sophie Brouillet Christophe Terzian Alain Hénaut 《Journal of molecular evolution》1997,44(2):214-225
A computer-assisted analysis was made of 24 complete nucleotide sequences selected from the vertebrate retroviruses to represent
the ten viral groups. The conclusions of this analysis extend and strengthen the previously made hypothesis on the Moloney
murine leukemia virus: The evolution of the nucleotide sequence appears to have occurred mainly through at least three overlapping
levels of duplication: (1) The distributions of overrepresented (3–6)-mers are consistent with the universal rule of a trend
toward TG/CT excess and with the persistence of a certain degree of symmetry between the two strands of DNA. This suggests
one or several original tandemly repeated sequences and some inverted duplications. (2) The existence of two general core
consensuses at the level of these (3–6)-mers supports the hypothesis of a common evolutionary origin of vertebrate retroviruses.
Consensuses more specific to certain sequences are compatible with phylogenetic trees established independently. The consensuses
could correspond to intermediary evolutionary stages. (3) Most of the (3–6)-mers with a significantly higher than average
frequency appear to be internally repeated (with monomeric or oligomeric internal iterations) and seem to be at least partly
the cause of the bias observed by other researchers at the level of retroviral nucleotide composition. They suggest a third
evolutionary stage by slippage-like stepwise local duplications.
Received: 3 January 1996 / Accepted: 27 March 1996 相似文献
14.
The phylogenetic position of hagfishes in vertebrate evolution is currently controversial. The 18S and 28S rRNA trees support
the monophyly of hagfishes and lampreys. In contrast, the mitochondrial DNAs suggest the close association of lampreys and
gnathostomes. To clarify this controversial issue, we have conducted cloning and sequencing of the four nuclear DNA–coded
single-copy genes encoding the triose phosphate isomerase, calreticulin, and the largest subunit of RNA polymerase II and
III. Based on these proteins, together with the Mn superoxide dismutase for which hagfish and lamprey sequences are available
in database, phylogenetic trees have been inferred by the maximum likelihood (ML) method of protein phylogeny. It was shown
that all the five proteins prefer the monophyletic tree of cyclostomes, and the total log-likelihood of the five proteins
significantly supports the cyclostome monophyly at the level of ±1 SE. The ML trees of aldolase family comprising three nonallelic
isoforms and the complement component group comprising C3, C4, and C5, both of which diverged during vertebrate evolution
by gene duplications, also suggest the cyclostome monophyly.
Received: 28 April 1999 / Accepted: 30 June 1999 相似文献
15.
Matthias Griese Stephanie Heinrich Felix Ratjen Michael Kabesch Karl Paul Manfred Ballmann Ernst Rietschel Matthias Kappler 《PloS one》2012,7(12)
Background
The state of oligomerization of surfactant associated protein-A (SP-A) monomers differs between individuals. This likely affects SP-A’s functional properties and could thereby influence clinical status in patients with lung diseases. In this study we focus on SP-A structure in cystic fibrosis (CF) compared to both healthy subjects and disease controls.Methods
SP-A composition and function were assessed in both bronchoalveolar lavage (BAL) fluid and serum of 46 CF patients with mild disease, 25 patients with chronic bronchitis and 22 healthy subjects by gel chromatography and a functional agglutination assay. Relation of SP-A agglutination ability to disease severity of the subjects was explored.Results
SP-A was present in seven major oligomeric forms with the majority of SP-A being structurally organized as complex oligomeric forms. More complex oligomeric forms were associated with better SP-A function with regard to its agglutination ability. These forms were more frequently observed in BAL than in serum, but there were no differences between disease groups. In CF patients, more complex forms of SP-A were associated with better lung function.Conclusions
Organizational structure of SP-A affects its functional activity and is linked to disease severity in CF. 相似文献16.
The Path from the RNA World 总被引:1,自引:0,他引:1
We describe a sequential (step by step) Darwinian model for the evolution of life from the late stages of the RNA world through
to the emergence of eukaryotes and prokaryotes. The starting point is our model, derived from current RNA activity, of the
RNA world just prior to the advent of genetically-encoded protein synthesis. By focusing on the function of the protoribosome
we develop a plausible model for the evolution of a protein-synthesizing ribosome from a high-fidelity RNA polymerase that
incorporated triplets of oligonucleotides. With the standard assumption that during the evolution of enzymatic activity, catalysis
is transferred from RNA → RNP → protein, the first proteins in the ``breakthrough organism' (the first to have encoded protein
synthesis) would be nonspecific chaperone-like proteins rather than catalytic. Moreover, because some RNA molecules that pre-date
protein synthesis under this model now occur as introns in some of the very earliest proteins, the model predicts these particular
introns are older than the exons surrounding them, the ``introns-first' theory. Many features of the model for the genome
organization in the final RNA world ribo-organism are more prevalent in the eukaryotic genome and we suggest that the prokaryotic
genome organization (a single, circular genome with one center of replication) was derived from a ``eukaryotic-like' genome
organization (a fragmented linear genome with multiple centers of replication). The steps from the proposed ribo-organism
RNA genome → eukaryotic-like DNA genome → prokaryotic-like DNA genome are all relatively straightforward, whereas the transition
prokaryotic-like genome → eukaryotic-like genome appears impossible under a Darwinian mechanism of evolution, given the assumption
of the transition RNA → RNP → protein. A likely molecular mechanism, ``plasmid transfer,' is available for the origin of
prokaryotic-type genomes from an eukaryotic-like architecture. Under this model prokaryotes are considered specialized and
derived with reduced dependence on ssRNA biochemistry. A functional explanation is that prokaryote ancestors underwent selection
for thermophily (high temperature) and/or for rapid reproduction (r selection) at least once in their history.
Received: 14 January 1997 / Accepted: 19 May 1997 相似文献
17.
The members of the PKA regulatory subunit family (PKA-R family) were analyzed by multiple sequence alignment and clustering
based on phylogenetic tree construction. According to the phylogenetic trees generated from multiple sequence alignment of
the complete sequences, the PKA-R family was divided into four subfamilies (types I to IV). Members of each subfamily were
exclusively from animals (types I and II), fungi (type III), and alveolates (type IV). Application of the same methodology
to the cAMP-binding domains, and subsequently to the region delimited by β-strands 6 and 7 of the crystal structures of bovine
RIα and rat RIIβ (the phosphate-binding cassette; PBC), proved that this highly conserved region was enough to classify unequivocally
the members of the PKA-R family. A single signature sequence, F–G–E–[LIV]–A–L–[LIMV]–x(3)–[PV]–R–[ANQV]–A, corresponding to
the PBC was identified which is characteristic of the PKA-R family and is sufficient to distinguish it from other members
of the cyclic nucleotide-binding protein superfamily. Specific determinants for the A and B domains of each R-subunit type
were also identified. Conserved residues defining the signature motif are important for interaction with cAMP or for positioning
the residues that directly interact with cAMP. Conversely, residues that define subfamilies or domain types are not conserved
and are mostly located on the loop that connects α-helix B′ and β strand 7.
Received: 2 November 2000/Accepted: 14 June 2001 相似文献
18.
Boris V. Skryabin Joachim Kremerskothen Dido Vassilacopoulou Todd R. Disotell Vladimir V. Kapitonov Jerzy Jurka Jürgen Brosius 《Journal of molecular evolution》1998,47(6):677-685
The gene encoding BC200 RNA arose from a monomeric Alu element. Subsequently, the RNA had been recruited or exapted into
a function of the nervous system. Here we confirm the presence of the BC200 gene in several primate species among the Anthropoidea.
The period following the divergence of New World monkeys and Old World monkeys from their common ancestor is characterized
by a significantly higher substitution rate in the examined 5′ flanking region than in the BC200 RNA coding region itself.
Furthermore, the conservation of CpG dimers in the RNA coding region (200 bp) is drastically increased compared to the 5′
flanking region (∼400 bp) over all 12 species examined. Finally, the brain-specific expression pattern of BC200 RNA and its
presence as a ribonucleoprotein particle (RNP) are conserved in Old World and New World monkeys. Our studies indicate that
the gene encoding BC200 RNA was created at least 35–55 million years ago and its presence, mode of expression, and association
with protein(s) as an RNP are under selective pressure.
Received: 1 December 1997 / Accepted: 3 June 1998 相似文献
19.
Michael D. Purugganan 《Journal of molecular evolution》1997,45(4):392-396
Flower development in angiosperms is controlled in part by floral homeotic genes, many of which are members of the plant
MADS-box regulatory gene family. The evolutionary history of these developmental genes was reconstructed using 74 loci from
15 dicot, three monocot, and one conifer species. Molecular clock estimates suggest that the different floral homeotic gene
lineages began to diverge from one another about 450–500 mya, around the time of the origin of land plants themselves.
Received: 31 January 1997 / Accepted: 9 April 1997 相似文献
20.
V. Marshansky A. Fleser J. Noël S. Bourgoin P. Vinay 《The Journal of membrane biology》1996,153(1):59-73
During the preparation of a suspension of dog kidney proximal tubules by collagenase treatment, an uptake of FITC-albumin
was demonstrated. This process is attributed to the activation of receptor-mediated endocytosis leading to the appearance
of FITC-albumin into intracellular vesicular structures. The isolation of brush border membrane vesicles (BBMV) from the dog
kidney proximal tubules in suspension by the magnesium precipitation technique leads to the copurification of a large population
of endosomes. These endosomes were separated from BBM vesicles by a technique involving wheat-germ agglutinin. The enrichment
in BBM markers and in bafilomycin-sensitive ATPase activity was comparable in endosomes and BBM vesicles. However, the acridine
orange acidification assay showed a V-type ATPase-dependent acidification in endosomes but not in BBMV, demonstrating a different
orientation of the proton pumps in these structures. SDS-PAGE analysis also showed significant differences in protein pattern
of vesicles and endosomes. The most notable difference was the presence of 42–44 kDa and 20–24 kDa proteins in BBMV and their
complete absence in endosomes. Western blot analysis identified these proteins as actin and RhoA, among other small proteins,
respectively. Western blot experiments also demonstrated a different distribution of β-COP, β-adaptin, and RhoGDI in vesicles
and endosomes. The morphological aspect (electron microscopy) and sedimentation of endosomes in a 50% Percoll gradient identified
these structures as ``heavy endosomes' (buoyant density D= 1.036 g/ml). Flow cytometry analysis of heavy endosomes purified from tubules isolated in presence of FITC-albumin showed
the presence of FITC-albumin in up to 92% of these intracellular organelles. Western blot analysis using anti-FITC and anti-collagenase
antibodies allowed quantification of the FITC-albumin and collagenase A in the purified endosomes. Our results indicate that
heavy endosomes are formed during the preparation of the proximal tubules following activation of receptor-mediated endocytosis,
probably by soluble proteins. The suspension of tubules thus offers a experimental tool to study the protein reabsorption
and traffic of endosomal vesicles in the proximal tubules.
Received: 13 July 1995/Revised: 8 May 1996 相似文献