Together with HP30-1 and HP20, triggers the import and insertion of transit sequence-less multi-pass transmembrane proteins (e.g. CEQORH) into the chloroplastic inner membrane. Probable component of a protein-conducting channel made of HP30-1, HP30-2 and HP20 that mediates the import of transit sequence-less proteins into the chloroplastic inner membrane. Interacts with CEQORH. Seems to be present both in chloroplast and mitochondrion. Plants lacking both HP30-1 and HP30-2 are yellow to pale-green and impaired import of CEQORH in chloroplast inner membranes. Belongs to the Tim17/Tim22/Tim23 family. Truncated N-terminus.