Abstract
J proteins are functional partners for Hsp70. Yeast has three J proteins in the ER: Scj1p and Jem1p functioning in the ER quality control, and Sec63p functioning in protein translocation across the ER membrane as partners for an Hsp70 in the ER. We found that A. thaliana has orthologs of these yeast ER J proteins. Since expression of AtERdj3A, AtERdj3B and AtP58IPK partially suppressed the growth defects of the yeast jem1Δ scj1Δ mutant, they appear to have functions similar to those of Scj1p and Jem1p. To examine the role in the ER quality control for the Arabidopsis growth, we analyzed T-DNA mutants of these J protein genes. We found that the aterdj3b mutants became sterile when they grew at high temperature. The aterdj3b mutants reduced the number of pollen grains attached to stigma.
