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  • flagella  (2)
  • Tubulin gene  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 214 (1988), S. 204-212 
    ISSN: 1617-4623
    Schlagwort(e): Chlamydomonas ; Tubulin gene ; Oocyte ; Microinjection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary 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.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 25 (1993), S. 158-170 
    ISSN: 0886-1544
    Schlagwort(e): acetylation ; epitope-tagging ; flagella ; tubulin isoforms ; microtubules ; rubisco ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Following the discovery of acetylated α-tubulin in the flagella of Chlamydomonas, many studies have documented the presence of acetylated α-tubulin in a variety of evolutionarily divergent organisms. While this posttranslational modification may define an isoform with a unique function, the primary effect of α-tubulin acetylation remains unknown. To study the function of α-tubulin acetylation, we have transformed Chlamydomoas, a organism in which almost all of the flagellar tubulin ad a subset of the cytoplasmic microtubules are acetylated, with a α1-tubulin gene whose product cannot be acetylated. Specifically, the codon for lysine 40, the lysine that is acetylated, has been replaced with the codons of nonacetylatable amino acids. To distinguish mutagenized α-tubulin from that produced by the two endogenous α-tubulin genes, mutant α-tubulin was tagged with an epitope from influenza virus hemagglutinin. Utilizing the constitutive Chlamydomonas rubisco small subunit S2 promoter, we have obtained in selected clones high levels of nonacetylatable α-tubulin expression approximating 50-70% of the total flagellar α-tubulin. Immunofluorescence and immunoblot analysis of transformed cells indicated that nonacetylatable α-tubulin could assemble, along with endogenous α-tubulin, into both cytoplasmic and flagellar microtubules. However, no gross phenotypic effects were observed, suggesting that the effect of α-tubulin acetylation is subtle. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 510-520 
    ISSN: 0886-1544
    Schlagwort(e): flagella ; motility ; dynein substructure ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: When outer-row dynein arms are extracted from Chlamydomonas flagellar axonemes, they dissociate into two ATPase complexes with sedimentation coefficients of 12S and 18S. We immunized mice with 18S dynein and generated a library of monoclonal antibodies against the polypeptides in this complex. Antibodies were selected which specifically recognize the 18S α- and β-heavy chains and the 83,000-dalton and 70,000-dalton intermediate chains. These antibodies were isolated and characterized for their ability to recognize determinants on both denatured antigens and native 18S dynein; 18S dynein was dissociated in stepwise fashion into smaller aggregates with ionic and nonionic detergents and the resulting subcomplexes were isolated by precipitation with specific monoclonal antibodies. The smallest aggregates isolated were heterodimers between the α-chain and a 16,000-dalton light chain and between the two intermediate chains. Additional close associations of the β-heavy chain with an 18,000-dalton light chain and 70,000-dalton intermediate chain, and a weaker interaction between the intermediate chain heterodimer and light chains of 21,000 daltons and 12,500 daltons, were also observed. We present a model of 18S dynein substructure based upon this information.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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