Abstract
DnaJ-like proteins are co-chaperons of hsp70s and regulate the chaperone functions of hsp70. The budding yeast, Saccharomyces cerevisiae, has 3 DnaJ-like proteins, Jem1p, Scj1p and Sec63p, in the endoplasmic reticulum (ER), which function as partners of BiP, a hsp70 in the ER. In yeast, BiP functions in multiple processes such as protein translocation, ER quality control and nuclear fusion during mating. We have shown that BiP funcions in different processes using different DnaJ-like proteins as partners. Analysis of the Arabidopsis genome sequence revealed the presence of genes which are supposed to be counterparts of Jem1p, Scj1p or Sec63p. We isolated cDNA clones of these genes using RT-PCR. All of these genes were induced by the tunicamycin treatment. We are currently analyzing whether expression of these genes suppresses the phenotypes of yeast mutants defective in the functions of DnaJ-like proteins in the ER.
