Chaperone receptor mediating Hsp90-dependent protein targeting to chloroplasts. Bi-functional preprotein receptor acting on both sides of the membrane. Part of the Toc complex and of the intermembrane space complex. Interacts with TOC12, TIC22 and with the cytosolic domain of TOC34 in a GTP dependent manner. Interacts (via TPR region) with HSP90 and with HSP70 with low efficiency. The TPR region (477-578) is not required for assembly into the Toc complex, but interacts with TOC34 only while transferring the preprotein from HSP90 to the Toc core translocon. The amidase region (166-200) is required for the efficient transfer of the preprotein.