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排序方式: 共有201条查询结果,搜索用时 940 毫秒
1.
Amino-terminal processing of proteins by N-myristoylation. Substrate specificity of N-myristoyl transferase 总被引:40,自引:0,他引:40
D A Towler S R Eubanks D S Towery S P Adams L Glaser 《The Journal of biological chemistry》1987,262(3):1030-1036
Using synthetic octapeptides, we examined the amino-terminal sequence requirements for substrate recognition by myristoyl-CoA:protein N-myristoyl transferase (NMT). NMT is absolutely specific for peptides with amino-terminal Gly residues. Peptides with Asn, Gln, Ser, Val, or Leu penultimate to the amino-terminal Gly were substrates, whereas peptides with Asp, D-Asn, Phe, or Tyr at this position were not myristoylated. Peptides with aromatic residues at this position competitively inhibited myristoylation of substrates, introducing the possibility of developing specific in vivo inhibitors of NMT. Peptides having sequences which correspond to those of known N-myristoyl proteins, including p60src, appear to be recognized by a single enzyme, and yeast and murine NMT have identical substrate specificities. The catalytic selectivity of NMT for myristoyl transfer accounts for the remarkable acyl chain specificity of this enzyme. 相似文献
2.
Haemophilus influenzae type b Minn A produced 12 lipoproteins with apparent molecular weights of between 14,000 and 67,000. The lipoproteins were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of delipidated extracts of cells grown in [3H]palmitate. When the delipidated cell extracts were subjected to acid methanolysis, tritium was quantitatively recovered as palmitate and methyl palmitate, indicating that the [3H]palmitate had not been degraded and reincorporated into nonlipid material during cell growth. One of the lipoproteins comigrated with outer membrane protein (OMP) P6. OMP P6 was purified from [3H]palmitate-labeled cells. The purified protein preparation contained both amide- and ester-linked fatty acids. We conclude that (i) H. influenzae type b produces several lipoproteins, and (ii) one of these lipoproteins is OMP P6, a protein under consideration as a vaccine component. 相似文献
3.
Acylation of cellular proteins with endogenously synthesized fatty acids 总被引:14,自引:0,他引:14
A number of cellular proteins contain covalently bound fatty acids. Previous studies have identified myristic acid and palmitic acid covalently linked to protein, the former usually attached to proteins by an amide linkage and the latter by ester or thio ester linkages. While in a few instances specific proteins have been isolated from cells and their fatty acid composition has been determined, the most frequent approach to the identification of protein-linked fatty acids is to biosynthetically label proteins with fatty acids added to intact cells. This procedure introduces possible bias in that only a selected fraction of proteins may be labeled, and it is not known whether the radioactive fatty acid linked to the protein is identical with that which is attached to the protein when the fatty acid is derived from endogenous sources. We have examined the distribution of protein-bound fatty acid following labeling with [3H]acetate, a general precursor of all fatty acids, using BC3H1 cells (a mouse muscle cell line) and A431 cells (a human epidermoid carcinoma). Myristate, palmitate, and stearate account for essentially all of the fatty acids linked to protein following labeling with [3H]acetate, but at least 30% of the protein-bound palmitate in these cells was present in amide linkage. In BC3H1 cells, exogenous palmitate becomes covalently bound to protein such that less than 10% of the fatty acid is present in amide linkage. These data are compatible with multiple protein acylating activities specific for acceptor protein fatty acid chain length and linkage.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
4.
We have broadly defined the DNA regions regulating esterase6 activity in
several life stages and tissue types of D. melanogaster using P-
element-mediated transformation of constructs that contain the esterase6
coding region and deletions or substitutions in 5' or 3' flanking DNA.
Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and
the primary sequences regulating its activity lie between -171 and -25 bp
relative to the translation initiation site: deletion of these sequences
decrease activity approximately 20-fold. Hemolymph activity is also
modulated by four other DNA regions, three of which lie 5' and one of which
lies 3' of the coding region. Of these, two have positive and two have
negative effects, each of approximately twofold. Esterase6 activity is
present also in two male reproductive tract tissues; the ejaculatory bulb,
which is another ancestral activity site, and the ejaculatory duct, which
is a recently acquired site within the melanogaster species subgroup.
Activities in these tissues are at least in part independently regulated:
activity in the ejaculatory bulb is conferred by sequences between -273 and
-172 bp (threefold decrease when deleted), while activity in the
ejaculatory duct is conferred by more distal sequences between -844 and
-614 bp (fourfold decrease when deleted). The reproductive tract activity
is further modulated by two additional DNA regions, one in 5' DNA (-613 to
-284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to
+2731 bp; threefold decrease when deleted) that probably overlaps the
adjacent esteraseP gene. Collating these data with previous studies
suggests that expression of EST6 in the ancestral sites is mainly regulated
by conserved proximal sequences while more variable distal sequences
regulate expression in the acquired ejaculatory duct site.
相似文献
5.
Litman GW; Rast JP; Shamblott MJ; Haire RN; Hulst M; Roess W; Litman RT; Hinds- Frey KR; Zilch A; Amemiya CT 《Molecular biology and evolution》1993,10(1):60-72
Immunoglobulins are encoded by a large multigene system that undergoes
somatic rearrangement and additional genetic change during the development
of immunoglobulin-producing cells. Inducible antibody and antibody-like
responses are found in all vertebrates. However, immunoglobulin possessing
disulfide-bonded heavy and light chains and domain-type organization has
been described only in representatives of the jawed vertebrates. High
degrees of nucleotide and predicted amino acid sequence identity are
evident when the segmental elements that constitute the immunoglobulin gene
loci in phylogenetically divergent vertebrates are compared. However, the
organization of gene loci and the manner in which the independent elements
recombine (and diversify) vary markedly among different taxa. One striking
pattern of gene organization is the "cluster type" that appears to be
restricted to the chondrichthyes (cartilaginous fishes) and limits
segmental rearrangement to closely linked elements. This type of gene
organization is associated with both heavy- and light-chain gene loci. In
some cases, the clusters are "joined" or "partially joined" in the germ
line, in effect predetermining or partially predetermining, respectively,
the encoded specificities (the assumption being that these are expressed)
of the individual loci. By relating the sequences of transcribed gene
products to their respective germ-line genes, it is evident that, in some
cases, joined-type genes are expressed. This raises a question about the
existence and/or nature of allelic exclusion in these species. The
extensive variation in gene organization found throughout the vertebrate
species may relate directly to the role of intersegmental
(V<==>D<==>J) distances in the commitment of the individual
antibody-producing cell to a particular genetic specificity. Thus, the
evolution of this locus, perhaps more so than that of others, may reflect
the interrelationships between genetic organization and function.
相似文献
6.
R J Duronio D A Rudnick S P Adams D A Towler J I Gordon 《The Journal of biological chemistry》1991,266(16):10498-10504
A dual plasmid system was used to examine the protein and acyl-CoA specificities of Saccharomyces cerevisiae myristoyl-CoA:protein N-myristoyltransferase (NMT) by co-expressing it in Escherichia coli with each of four homologous alpha subunits of the signal-transducing, heterotrimeric G proteins. Exogenous [3H]myristate was incorporated into rat Gi alpha 1 and rat Go alpha but not into bovine Gs alpha or human Gz alpha. Oxygen for methylene group substitutions in myristate result in analogs with comparable chain length and stereochemistry but marked reductions in hydrophobicity. Metabolic labeling studies with 6-, 11-, or 13-[3H]oxatetradecanoic acid indicated that they were incorporated into rat Gi alpha 1 and Go alpha with an efficiency that could be correlated with their accumulation into E. coli and their interactions with purified NMT in vitro. Octapeptides derived from the NH2-terminal sequences of these four G alpha polypeptides were tested as substrates for purified S. cerevisiae NMT. None were bound by the enzyme. Acidic residues at positions 7 and 8 appear to contribute to this effect; deletion of these two amino acids or addition of the next 9 residues of rat Go alpha produced active substrates. These results imply that productive interactions between NMT and G alpha protein substrates in vivo require structural features that are not fully represented within their NH2-terminal 8 residues. 相似文献
7.
R O Heuckeroth D A Towler S P Adams L Glaser J I Gordon 《The Journal of biological chemistry》1988,263(5):2127-2133
The covalent attachment of myristic acid to the NH2-terminal glycine residue of proteins is catalyzed by the enzyme myristoyl CoA:protein N-myristoyltransferase (NMT). Using synthetic octapeptide substrates we have identified and characterized an NMT activity in wheat germ lysates used for cell-free translation of exogenous mRNAs. C-12 and C-14 fatty acids are efficiently transferred to the peptides by this plant NMT, but C-10 and C-16 fatty acids are not. Glycine is required as the NH2-terminal residue: peptides with an NH2-terminal alanine were not substrates. Peptides with proline, aspartic acid, or tyrosine residues adjacent to the NH2-terminal glycine were also not myristoylated. Serine in the fifth position reduced the peptide's Km up to 4000-fold. We have chemically synthesized a sulfur analogue of myristate, 11-(ethylthio)undecanoic acid. Its CoA ester is as good a substrate as myristoyl-CoA for both wheat germ and yeast NMT. Peptides linked to 11-(ethylthio)undecanoic acid are less hydrophobic than the corresponding myristoylpeptides. 11-(Ethylthio)-undecanoic acid may, therefore, help define the role of myristic acid in targeting of acyl proteins within cells. 相似文献
8.
Schistosomiasis vector snails are subjected to extreme seasonal changes, particularly in ephemeral rivers and lentic waterbodies. In the tropics, aestivation is one of the adaptive strategies for survival and is used by snails in times of extremely high temperatures and desiccation. Aestivation therefore plays an important role in maintaining the transmission of schistosomiasis. This review assesses the possible impacts of climate change on the temporal and spatial distribution of schistosomiasis-transmitting snails with special emphasis on aestivation, and discusses the effect of schistosome infection on aestivation ability. The impacts of parasite development on snails, as well as physiological changes, are discussed with reference to schistosomiasis transmission. This review shows that schistosome-infected snails have lower survival rates during aestivation, and that those that survive manage to get rid of the infection. In general, snail aestivation ability is poor and survival chances diminish with time. Longer dry periods result in fewer, as well as uninfected, snails. However, the ability of the surviving snails to repopulate the habitats is high. 相似文献
9.
Attenuation of pattern recognition receptor signaling is mediated by a MAP kinase kinase kinase 下载免费PDF全文
Sharon C Mithoe Christina Ludwig Michiel JC Pel Mara Cucinotta Alberto Casartelli Malick Mbengue Jan Sklenar Paul Derbyshire Silke Robatzek Corné MJ Pieterse Ruedi Aebersold Frank LH Menke 《EMBO reports》2016,17(3):441-454
Pattern recognition receptors (PRRs) play a key role in plant and animal innate immunity. PRR binding of their cognate ligand triggers a signaling network and activates an immune response. Activation of PRR signaling must be controlled prior to ligand binding to prevent spurious signaling and immune activation. Flagellin perception in Arabidopsis through FLAGELLIN‐SENSITIVE 2 (FLS2) induces the activation of mitogen‐activated protein kinases (MAPKs) and immunity. However, the precise molecular mechanism that connects activated FLS2 to downstream MAPK cascades remains unknown. Here, we report the identification of a differentially phosphorylated MAP kinase kinase kinase that also interacts with FLS2. Using targeted proteomics and functional analysis, we show that MKKK7 negatively regulates flagellin‐triggered signaling and basal immunity and this requires phosphorylation of MKKK7 on specific serine residues. MKKK7 attenuates MPK6 activity and defense gene expression. Moreover, MKKK7 suppresses the reactive oxygen species burst downstream of FLS2, suggesting that MKKK7‐mediated attenuation of FLS2 signaling occurs through direct modulation of the FLS2 complex. 相似文献
10.