Mitochondrial Hsp70 cannot replace BiP in driving protein translocation into the yeast endoplasmic reticulum

FEBS Letters

Bäuerle, Marc¹  Brodsky, Jeffrey L²  McClellan, Amie J²  Horst, Martin¹ 

[1] Georg-August Universität Göttingen, Zentrum für Biochemie und Molekulare Zellbiologie, Abteilung Biochemie II, Gosslerstr. 12D, 37073 Göttingen, Germany;Department of Biological Sciences, University of Pittsburgh, 267 Crawford Hall, Pittsburgh, PA 15260, USA

关键词: Protein translocation;    Heat shock protein;    BiP;    mHsp70;    Endoplasmic reticulum;   

DOI  :  10.1016/S0014-5793(98)01065-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

To determine whether mitochondrial hsp70 (mHsp70) could substitute for the endoplasmic retuculum (ER) Hsp70 (BiP) during protein translocation, we assembled ER-derived reconstituted proteoliposomes supplemented with either protein. We found that only BiP restored translocation in kar2 mutant vesicles and stimulated translocation ∼3-fold in wild type proteoliposomes. mHsp70 associated poorly with both a BiP binding (DnaJ) domain of Sec63p and an ER precursor, and its ATPase activity was poorly enhanced upon incubation with the DnaJ domain. In contrast, BiP bound to the Sec63p-DnaJ domain in an ATP-dependent manner and its ATPase activity was stimulated significantly by this polypeptide. We conclude that mHsp70 is unable to support protein translocation into the ER because it fails to associate productively with Sec63p and a precursor.

【 授权许可】

Unknown