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Isolation of a cDNA clone specifying rat chaperonin 10, a stress‐inducible mitochondrial matrix protein synthesised without a cleavable presequence
Author(s) -
Ryan Michael T.,
Hoogenraad Nicholas J.,
Høj Peter B.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80263-7
Subject(s) - chaperonin , complementary dna , mitochondrial matrix , amino acid , biology , mitochondrion , biochemistry , heat shock protein , microbiology and biotechnology , methionine , gene , enzyme , cytosol
We have isolated a cDNA clone encoding chaperonin 10 from rat liver. The cDNA specifies a protein of 102 amino acids which, when transcribed and translated in vitro, yields a single basic product (pI > 9) that co‐migrates exactly with the heat shock inducible cpn10 of rat hepatoma cells during 2D gel‐electrophoresis. It is concluded that cpn10, unlike the majority of nuclear‐encoded proteins of the mitochondrial matrix, is synthesised without a cleavable targeting signal and that, following removal of the initiating methionine, it becomes acetylated prior to mitochondrial import. Incubation of 3 H‐ or 35 S‐labelled cpn10 with mitochondria confirms these conclusions and shows that cpn10 is imported into mitochondria in an energy‐dependent process which is inhibited by the presence of 2,4‐dinitrophenol.