Send to

Choose Destination
EMBO J. 1995 Jul 17;14(14):3434-44.

Hsp78, a Clp homologue within mitochondria, can substitute for chaperone functions of mt-hsp70.

Author information

Institut für Physiologische Chemie der Universität München, Germany.


Hsp78 is a Clp homologue within mitochondria of Saccharomyces cerevisiae. Deletion of HSP78 does not cause any detectable changes in wild type cells, but results in a petite phenotype in the ssc1-3 mutant strain carrying a temperature-sensitive allele of mt-hsp70. When overexpressed in the ssc1-3 mutant strain, hsp78 suppresses the defect in mitochondrial protein import under permissive conditions in vitro and interacts directly with newly imported polypeptide chains. As a molecular chaperone, hsp78 prevents the aggregation of misfolded proteins in the matrix of mitochondria under conditions of impaired mt-hsp70 function. However, unlike misfolded proteins associated with mt-hsp70, hsp78-bound polypeptides are not efficiently degraded by the ATP-dependent PIM1 protease. Thus, hsp78 can partially substitute for mt-hsp70 functions in the assembly of mitochondria and may be part of a salvage pathway if mt-hsp70 is limiting.

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center