YDJ1p facilitates polypeptide translocation across different intracellular membranes by a conserved mechanism.
The role of S. cerevisiae YDJ1 protein (YDJ1p) in polypeptide translocation across membranes has been examined. A conditional ydj1 mutant strain (ydj1-151TS) is defective for import of several polypeptides into mitochondria and alpha factor into the endoplasmic reticulum at 37 degrees C. These defects are suppressed by E. coli dnaJ or overexpression of S. cerevisiae SIS1 proteins. A different ydj1 mutant, which cannot be farnesylated (ydj1-S406), displays similar transport defects to the ydj1-151 strain. Furthermore, the ability of purified ydj1-151p to stimulate the ATPase activity of hsp70SSA1 was greatly diminished compared with the wild-type protein. Together, these data suggest that YDJ1p functions in polypeptide translocation in a conserved manner, probably acting at organelle membranes and in association with hsp70 proteins.
Caplan
A J
AJ
Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599-7260.
Cyr
D M
DM
Douglas
M G
MG
D000818:Animals; D001692:Biological Transport; D004252:DNA Mutational Analysis; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004926:Escherichia coli; D005656:Fungal Proteins / Q000378:metabolism*; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D012440:Saccharomyces / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; C070319:YDJ1 protein, S cerevisiae