POSTTRANSLATIONAL PROTEIN IMPORT AND FOLDING

Significant advances have been made over the past year in analyzing th e membrane machineries for the post-translational export of proteins i n bacteria and for the import of proteins into mitochondria. Another i mportant development is the identification in mitochondria of homologs of the bacterial heat-shock proteins DnaJ and GrpE, which function to gether with Hsp70 in membrane translocation and folding of imported pr oteins. A number of gene products involved in peroxisomal protein upta ke have been identified, which are now awaiting biochemical analysis.