Subunits of the eukaryotic cytosolic chaperonin CCT do not always behave as components of a uniform hetero-oligomeric particle

Roobol, Anne and Carden, Martin J. (1999) Subunits of the eukaryotic cytosolic chaperonin CCT do not always behave as components of a uniform hetero-oligomeric particle. European Journal of Cell Biology, 78 (1). pp. 21-32. ISSN 0171-9335. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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The chaperonin CCT is an hetero-oligomeric molecular chaperone complex. Studies in yeast suggest each of its eight gene products are required for its major identified functions in producing native tubulins and actins, However, it is unclear whether these eight components always form a single particle, covering all functions, or else can also exist as heterogeneous mixtures and/or free subunits in cells. Using mouse P19 embryonal carcinoma cells, which divide rapidly, yet in retinoic acid adopt a neuronal phenotype, admired with occasional (similar to 10 %) fibroblast-like cells, together with a panel of peptide-specific antibodies raised to 7 of the 8 CCT subunits we show that; (1) adoption of a post mitotic phenotype is accompanied by reduced CCT protein expression, significantly more so for CCT beta, CCT delta, CCT epsilon, and CCT theta than for CCT alpha (TCP-1), CCT gamma and CCT zeta; (2) CCT alpha is detected preferentially over other subunits in neurites of P19 neurons; (3) small amounts of CCT alpha and gamma are localised in nuclei (i.e. are not exclusively cytoplasmic), selectively so compared with other subunits; (4) numerous cytosolic foci exist in the cytoplasm which, when detected by double immunofluorescence can contain only one of the subunits probed for; (5) while a "core" chaperonin particle can be immunoprecipitated under native conditions, epitope access is modified both by nucleotides and by non-CCT co-precipitating proteins. Collectively, these findings indicate that CCT subunits are not only components of the hetero-oligomeric chaperonin particle but exist as significant populations of free subunits or smaller oligomers in cells.

Item Type: Article
Uncontrolled keywords: molecular chaperone; P19 cells; neuritogenesis; cytoskeleton; protein folding and assembly
Subjects: Q Science
Q Science > QH Natural history > QH301 Biology
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: F.D. Zabet
Date Deposited: 15 Apr 2009 11:32
Last Modified: 14 May 2014 09:39
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