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961.
Characterization of a pollen-specific gene family from Brassica napus which is activated during early microspore development 总被引:13,自引:0,他引:13
Diego Albani Laurian S. Robert Pauline A. Donaldson Illimar Altosaar Paul G. Arnison Steven F. Fabijanski 《Plant molecular biology》1990,15(4):605-622
In this paper we describe the isolation and characterization of a genomic clone (Bp4) from Brassica napus which contains three members of a pollen-specific multigene family. This family is composed of 10 to 15 closely related genes which are expressed in early stages of microspore development. The complete nucleotide sequence of the clone Bp4 and of three homologous cDNA clones is reported. One of the genes (Bp4B) contained in the genomic clone is believed to be non-functional because of sequence rearrangements in its 5 region and intron splicing sites. The remaining genes (Bp4A and Bp4C), as well as the cDNA clones, appear to code for small proteins of unique structure. Three different types of proteins can be predicted as a result of the deletion of carboxy or amino terminal portions of a conserved core protein. These proteins all share a common alternation of hydrophobic and hydrophilic domains. A fragment of the genomic clone containing the gene Bp4A, as well as the non-functional gene Bp4B, was introduced into tobacco plants via Agrobacterium-mediated transformation. The functional gene Bp4A is expressed in transgenic tobacco plants and shows spatial and temporal regulation consistent with the expression patterns seen in Brassica napus. 相似文献
962.
Previously, a ferredoxin-type iron-sulfur protein, frx B protein, was identified in a high-salt extract of the purified thylakoid membrane of Chlamydomonas reinhardtii, a unicellular green alga. Polyclonal antibody was raised against a synthetic pentadecameric peptide with an amino acid sequence corresponding to the highly conserved region of the putative frx B proteins of 3 land plants [21]. In this report, protein(s) reacting strongly and specifically with this antibody was detected in the equivalent high-salt extract prepared from purified chloroplast of spinach and tobacco. One strong reaction polypeptide band from tobacco chloroplast was purified from SDS-polyacrylamide gel and subjected to endoproteinase lys C digestion. The resulting polypeptides were separated by reversed-phase chromatography. N-terminal sequencing of 3 purified polypeptides revealed that the protein is encoded by the frxB gene identified from DNA sequence analysis. 相似文献
963.
U. Gartenbach-Scharrer S. Habib K. -H. Neumann 《Plant Cell, Tissue and Organ Culture》1990,22(1):27-35
Freshly isolated explants of the secondary phloem of carrot roots were exposed to 14C-leucine for various periods from t0—to 18 h and the 14C labelling of protein was studied by 2-dimensional PAGE followed by fluorograph. The labelling pattern of proteins indicated a sequential activation of synthesis of about 130 proteins during the 18 h experimental period prior to the onset of cell division activity.Abbreviations IAA
indole acetic acid
- 2iP
2-isopentenyladenine
- PVP
polyvinylpyrrolidone
- CBB
Coomassie brilliant blue
- RuBPCase
ribulosebisphosphate carboxylase
- LSC
liquid scintillation counter
- spec.act.
specific radioactivity
- u.l.
uniformly labelled 相似文献
964.
Philip J. Bassford Jr. 《Journal of bioenergetics and biomembranes》1990,22(3):401-439
The export of the maltose-binding protein (MBP), themalE gene product, to the periplasm ofEschericha coli cells has been extensively investigated. The isolation of strains synthesizing MalE-LacZ hybrid proteins led to a novel genetic selection for mutants that accumulate export-defective precursor MBP (preMBP) in the cytoplasm. The export defects were subsequently shown to result from alterations in the MBP signal peptide. Analysis of these and a variety of mutants obtained in other ways has provided considerable insight into the requirements for an optimally functional MBP signal peptide. This structure has been shown to have multiple roles in the export process, including promoting entry of preMBP into the export pathway and initiating MBP translocation across the cytoplasmic membrane. The latter has been shown to be a late event relative to synthesis and can occur entirely posttranslationally, even many minutes after the completion of synthesis. Translocation requires that the MBP polypeptide exist in an export-competent conformation that most likely represents an unfolded state that is not inhibitory to membrane transit. The signal peptide contributes to the export competence of preMBP by slowing the rate at which the attached mature moiety folds. In addition, preMBP folding is thought to be further retarded by the binding of a cytoplasmic protein, SecB, to the mature moiety of nascent preMBP. In cells lacking this antifolding factor, MBP export represents a race between delivery of newly synthesized, export-competent preMBP to the translocation machinery in the cytoplasmic membrane and folding of preMBP into an export-incompetent conformation. SecB is one of threeE. coli proteins classified as molecular chaperones by their ability to stabilize precursor proteins for membrane translocation. 相似文献
965.
Thymocyte growth peptide (TGP) initiates DNA synthesis in immature thymocytes and has previously been characterized as an acidic peptide isolated from calf thymus. We now report the isolation of TGP from sheep thymus and show it to be a nonapeptide with a large N-terminal blocking moiety characterized by high UV absorbance. The amino acid composition is identical to FTS, consisting of 2 Gly, 2 Ser, 2 Glx, 1 Ala, 1 Lys, 1 Asx. In contrast to FTS, TGP is acidic with an apparent isoelectric point of 4.2 and a high UV absorbance at 270–280 nm. Reverse phase chromatography of TGP at an acidic pH results in a change of the molecule and the appearance of two new compounds TGP-A and TGP-B, both with less than 50% of the original TGP activity. Full activity could be restored by the addition of ZnCl2 to TGP-A. Both TGP-A and B have some amino acid composition and high UV absorbance as native TGP. We propose that TGP consists of a non-peptide moiety bound to the N-terminal of the nonapeptide Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn and that the active molecule is stabilized by Zn2+. 相似文献
966.
The specific binding of vasoactive intestinal peptide (VIP) to bovine thyroid plasma membranes is inhibited by guanine nucleotides. Guanosine 5-triphosphate (GTP) and the non-hydrolyzable GTP analogs guanosine 5-,-imidotriphosphate (Gpp(NH)p) and guanosine 5-O-(3-thiotriphosphate) (GTP--S) inhibited markedly the binding of VIP to its receptors. This inhibition was higher with GTP than with Gpp(NH)p and GTP--S and was due to an increase of the rate of dissociation of peptide bound to membranes. Other nucleotides did not show any effect. 相似文献
967.
Cholesterol as a target for toxins 总被引:2,自引:0,他引:2
B. de Kruijff 《Bioscience reports》1990,10(2):127-130
A mechanism is proposed for the way in which cholesterol facilitates channel formation by polyene antibiotics and bacterial protein toxins. Central elements of the model are: (i) interactions between the ring system of the sterol and rigid elements of the polyene or toxin molecule, and (ii) the specific orientation of cholesterol within the membrane. 相似文献
968.
Localized transient expression of GUS in leaf discs following cocultivation with Agrobacterium 总被引:15,自引:0,他引:15
A chimaeric gene has been constructed that expresses -D-glucuronidase (GUS) in transformed plant tissues, but not in bacterial cells. This gene has proved extremely useful for monitoring transformation during the period immediately following gene transfer from Agrobacterium tumefaciens. GUS expression was detectable 2 days after inoculation, peaked at 3–4 days and then declined; if selection was imposed expression increased again after 10–14 days. The extent of transient expression after 4 days correlated well with stable integration as measured by kanamycin resistance, hormone independence, and gall formation. Histochemical staining of inoculated leaf discs confirmed the transient peak of GUS expression 3–4 days after inoculation. The most surprising result was that the blue staining was concentrated in localized zones on the circumference of the disc; within these zones, essentially all the cells appeared to be expressing GUS. We suggest that the frequency of gene transfer from Agrobacterium is extremely high within localized regions of leaf explants, but that the frequency of stable integration is several orders of magnitude lower. 相似文献
969.
970.