Disassembly of the cytosolic chaperonin in mammalian cell extracts at intracellular levels of K+ and ATP

Roobol, A. and Grantham, J. and Whitaker, H.C. and Carden, M.J. (1999) Disassembly of the cytosolic chaperonin in mammalian cell extracts at intracellular levels of K+ and ATP. Journal of Biological Chemistry, 274 (27). pp. 19220-19227. ISSN 0021-9258. (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/10.1074/jbc.274.27.19220

Abstract

The eukaryotic, cytoplasmic chaperonin, CCT, is essential for the biogenesis of actin- and tubulin-based cytoskeletal structures. CCT purifies as a doubly toroidal particle containing two eight-membered rings of similar to 60-kDa ATPase subunits, each encoded by an essential and highly conserved gene. However, immunofluorescence detection with subunit-specific antibodies has indicated that in cells CCT subunits do not always colocalize. We report here that CCT ATPase activity is highly dependent on K+ ion concentration and that in cell extracts, at physiological levels of K+ and ATP, there is considerable dissociation of CCT to a smaller oligomeric structure and free subunits. This dissociation is consequent to ATP hydrolysis and is readily reversed on removal of ATP. The ranking order for ease with which subunits can exit the chaperonin particle correlates well with the length of a loop structure, identified by homology modeling, in the intermediate domain of CCT subunits. K+-ATP-induced disassembly is not an intrinsic property of purified CCT over a 80-fold concentration range and requires the presence of additional factor(s) present in cell extracts.

Item Type: Article
Subjects: Q Science
Q Science > QD Chemistry
Q Science > QH Natural history > QH301 Biology
Q Science > QR Microbiology
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: F.D. Zabet
Date Deposited: 15 Apr 2009 11:17
Last Modified: 15 Apr 2009 11:17
Resource URI: http://kar.kent.ac.uk/id/eprint/16565 (The current URI for this page, for reference purposes)
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