Plays a role in protein import into the endoplasmic reticulum (ER). May function as chaperone docking protein during post-translational protein translocation into the ER. Chaperone receptor mediating Hsp70-dependent protein targeting to chloroplasts. Interacts specifically with some chloroplast precursors, but not with mitochondrial precursors. Able to select precursors for delivery to the chloroplast translocase independently of Hsp70. Interacts (via TPR region) with HSP70-1, but not with HSP90-2. Interacts with ERDJ2A and ERDJ2B. In the ER membrane, associates with ERDJ2 in membrane complexes of 140 and 200 kDa and specifically interacts with the HSP70 and HSP90 chaperones via its TPR domain. Resides most likely exclusively in the ER membrane. Ubiquitous. Highest expression in leaves and lowest in roots. The TPR region (103-213) is necessary for interaction with HSP70-1 while the linker domain (214-530) facilitates selective recognition of chloroplast precursor complexes. Truncated N-terminus.