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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alpha-1 tubulin is the principal alpha-tubulin isotype found in the flagella of the unicellular green alga, Chlamydomonas reinhardii. Although the pattern of tubulin mRNA accumulation and utilization has been examined in some detail in Chlamydomonas (Lefebvre and Rosenbaum 1986), the transcriptional mechanisms establishing tubulin mRNA levels are not understood. To begin an analysis of the alpha-1 tubulin gene transcriptional control elements, we studied a number of promoter mutants of this gene from Chlamydomonas. These mutants, assayed by injection into Xenopus oocyte nuclei, delimit the promoter to 36 bp of DNA upstream of the cap site and 73 bp of the untranslated mRNA leader. A major rate-controlling element lies in a short GC-rich sequence positioned between the TATA homology and the mRNA cap site (position + 1). A similar sequence motif has been found in the same position upstream of all four tubulin genes of Chlamydomonas (Brunke et al. 1984). A 10 bp linker insertion within this sequence abolishes transcription. A far upstream sequence, located in a fragment between -400 and -800, is an efficiency element, whose deletion inhibits transcription in vivo by about 30%. The upstream element (ue) also has the unique ability to drive RNA polymerase II (RNAPII) transcription in vivo when isolated from all downstream promoter elements, unlike any control element described to date. These results suggest that a sequence within the upstream element is an entry site for RNAPII into the tubulin transcription unit.
Mol Gen Genet 1988 Oct
PMID:Novel control elements in the alpha-1 tubulin gene promoter from Chlamydomonas reinhardii. 323 8

Microtubules in yeasts are essential components of the mitotic and meiotic spindle and are necessary for nuclear movement during cell division and mating. The yeast Saccharomyces cerevisiae has two alpha-tubulin genes, TUB1 and TUB3, either of which alone is sufficient for these processes when present in a high enough copy number. Comparisons of sequences from several species reveals the presence of a variable region near the amino terminus of alpha-tubulin proteins. We perturbed the structure of this region in TUB3 by inserting into it 3, 9, or 17 amino acids and tested the ability of these altered proteins to function as the only alpha-tubulin protein in yeast cells. We found that each of these altered proteins was sufficient on its own for mitotic growth, mating, and methods of yeast. We conclude that this region can tolerate considerable variation without losing any of the highly conserved functions of alpha-tubulin. Our results suggest that variability in this region occurs because it can be tolerated, not because it specifies an important function for the protein.
Mol Cell Biol 1987 Oct
PMID:Insertions of up to 17 amino acids into a region of alpha-tubulin do not disrupt function in vivo. 331 88

Sequence analysis of a mouse testicular alpha-tubulin partial cDNA, pRD alpha TT1, reveals an isotype that differs from both the somatic and the predominant testicular alpha tubulins at approximately 30% of the 212 amino acid residues determined. Although this mouse testicular cDNA retains the highly conserved sequence, Glu-Gly-Glu-Glu, found in the carboxyl termini of many alpha tubulins, the protein extends substantially beyond this sequence and does not terminate with a C-terminal tyrosine. Using rabbit antiserum prepared to a novel synthetic peptide predicted from this mouse testis alpha-tubulin cDNA, we have have detected by immunoblot and indirect immunofluorescence an antigenic epitope present in testicular alpha tubulin that is not detectable in brain alpha tubulins. We find that the antiserum specifically binds to the manchettes and meiotic spindles of the mouse testis but not with neural fibers or tubulin extracts of the adult mouse brain. These results demonstrate that at least one of the multiple alpha-tubulin isotypes of the mammalian testis is expressed and used in male germ cells but not in the brain.
Mol Cell Biol 1988 Feb
PMID:Localization of a highly divergent mammalian testicular alpha tubulin that is not detectable in brain. 335 10

During the cell cycle of the Physarum polycephalum plasmodium, levels of alpha-tubulin mRNA rise exponentially in G2 phase, reach a peak at metaphase 40-fold above basal levels, and then fall exponentially to basal levels after mitosis. We show that post-mitotic alpha-tubulin mRNA carries poly(A) tracts of less than 30 residues. By contrast, when levels of alpha-tubulin mRNA rise during G2 phase, the mRNA has a poly(A) tract of approximately 80 bases. The length of the poly(A) tract of any mRNA encoding actin is relatively constant at fewer than 30 bases through the cycle. We have estimated the apparent rate of synthesis of alpha-tubulin mRNA at different stages of the cell cycle by short-term labeling in vivo. Transcription of alpha-tubulin mRNA continues even after mitosis, though the rate may be diminished relative to that in late G2 phase. So, the post-mitotic molecular half-life of alpha-tubulin mRNA must be less than the 19 minute half-life by which the levels of this species fall. The fact that the apparent rate of alpha-tubulin mRNA synthesis is not vastly greater in early G2 phase than in post-mitotic plasmodia is consistent with an S-phase destabilization of alpha-tubulin mRNA molecules. Thus, the poly(A) tail is shorter when the alpha-tubulin mRNA is less stable.
J Mol Biol 1988 Mar 20
PMID:Correlation between tubulin mRNA stability and poly(A) length over the cell cycle of Physarum polycephalum. 337 32

Tubulin was estimated to account for 16.3% and 0.25% of protein in rat brain and Nippostrongylus brasiliensis supernatants, respectively. Tubulin from N. brasiliensis and rat brain have been partially purified using polylysine agarose chromatography and high performance liquid chromatography on a gel permeation column. Western blots with alpha- and beta-tubulin monoclonal antibodies confirmed the presence of tubulin in different fractions. The mobility of N. brasiliensis tubulin on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was similar to that of rat brain tubulin. The isoelectric range for N. brasiliensis alpha- and beta-tubulin isoforms was pH 5.4-4.8 and pH 4.8-4.7, respectively. However, for rat brain the corresponding ranges were pH 5.4-4.9 and pH 5.0-4.6, respectively. Western blots with anti-tubulin monoclonal antibodies revealed 8 isoforms of alpha-tubulin and 3 isoforms of beta-tubulin for N. brasiliensis and 14-15 and 7-8 isoforms for rat brain alpha- and beta-tubulins, respectively. Different peptide maps were obtained for N. brasiliensis tubulin compared with rat brain tubulin.
Mol Biochem Parasitol 1988 Jun
PMID:Comparison of the properties of tubulin from Nippostrongylus brasiliensis with mammalian brain tubulin. 341 74

We have studied the fundamentals of gene expression in the protozoan parasite Toxoplasma gondii by analyzing, in detail, the genes encoding alpha- and beta-tubulin. Southern analysis and quantitation studies reveal that, unlike in other organisms studied thus far, both these genes are present as single copies in the haploid Toxoplasma genome. Sequencing of these genes indicates that they both contain multiple introns with conserved 5' and 3' splice site signals. We have found that HeLa cell nuclear extracts are able to accurately splice a Toxoplasma pre-mRNA construct. We have mapped, for the alpha-tubulin gene, the exact site of transcription initiation and the approximate site of poly A addition by primer extension and RNase protection assays. Trans-splicing, as demonstrated in the Kinetoplastida, is not involved in the formation of the mature alpha-tubulin transcript in T. gondii.
Mol Biochem Parasitol 1988 Jun
PMID:The alpha- and beta-tubulins of Toxoplasma gondii are encoded by single copy genes containing multiple introns. 341 77

Two categories of mitogen-induced mRNAs were defined in T lymphocytes. The type 1 messages (represented by c-myc) were regulated transcriptionally, and their expression seemed to be calmodulin dependent. The type 2 messages (ornithine decarboxylase, actin, and alpha-tubulin) were regulated posttranscriptionally through activation of protein kinase C.
Mol Cell Biol 1987 Aug
PMID:Different early-signaling pathways coupled to transcriptional and posttranscriptional regulation of gene expression during mitogenic activation of T lymphocytes. 349 67

Microtubules in yeast are essential components of the mitotic and meiotic spindles and are essential for nuclear movement during cell division and mating. The relative importance in these processes of the two divergent alpha-tubulin genes of the budding yeast Saccharomyces cerevisiae, TUB1 and TUB3, was examined through the construction of null mutations and by increasing their copy number on chromosomes and on plasmids. Experiments with null alleles of TUB3 showed that TUB3 was not essential for mitosis, meiosis, or mating. Null alleles of TUB3, however, did cause several phenotypes, including hypersensitivity to the antimicrotubule drug benomyl and poor spore viability. On the other hand, the TUB1 gene was essential for growth of normal haploid cells. Even in diploids heterozygous for a TUB1 null allele, several dominant phenotypes were evident, including slow growth and poor sporulation. This functional difference between the two genes is apparently due to different levels of expression, because extra copies of either gene could suppress the defects caused by a null mutation in the other. We conclude that in spite of the 10% divergence between the products of the two genes, there is no essential qualitative functional difference between them.
Mol Cell Biol 1986 Nov
PMID:Genetically essential and nonessential alpha-tubulin genes specify functionally interchangeable proteins. 354 Jun

The expression and cytological distribution of acetylated alpha-tubulin was investigated in Physarum polycephalum. A monoclonal antibody specific for acetylated alpha-tubulin, 6-11B-1 (Piperno, G., and M. T. Fuller, 1985, J. Cell Biol., 101:2085-2094), was used to screen for this protein during three different stages of the Physarum life cycle--the amoeba, the flagellate, and the plasmodium. Western blots of two-dimensional gels of amoebal and flagellate proteins reveal that this antibody recognizes the alpha 3 tubulin isotype, which was previously shown to be formed by posttranslational modification (Green, L. L., and W. F. Dove, 1984, Mol. Cell. Biol., 4:1706-1711). Double-label immunofluorescence demonstrates that, in the flagellate, acetylated alpha-tubulin is localized in the flagella and flagellar cone. Similar experiments with amoebae interestingly reveal that only within the microtubule organizing center (MTOC) are there detectable amounts of acetylated alpha-tubulin. In contrast, the plasmodial stage gives no evidence for acetylated alpha-tubulin by Western blotting or by immunofluorescence.
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PMID:Distribution of acetylated alpha-tubulin in Physarum polycephalum. 354 25

On the basis of analysis of cDNA clones of alpha-tubulin RNAs expressed during spermiogenesis in chickens, we report the identification of a novel alpha-tubulin which is expressed exclusively in chicken testes. Comparison of its sequence with those previously determined not only demonstrates that the encoded polypeptide is significantly divergent from other alpha-tubulins but also supports the hypothesis that alpha-tubulin isotypes are distinguished by a carboxy-terminal variable region sequence and, to a lesser extent, by a domain near the amino terminus. Since essentially all previously known alpha-tubulins undergo a unique cycle of removal and posttranslational readdition of a tyrosine residue at the extreme carboxy terminus, the presence in this testes alpha-tubulin of a very divergent carboxy terminus that does not contain an encoded tyrosine raises the possibility that this polypeptide does not participate in the usual cycle of tyrosination/detyrosination.
Mol Cell Biol 1987 Jan
PMID:A divergent testis-specific alpha-tubulin isotype that does not contain a coded C-terminal tyrosine. 356 2


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