Part of the inner chloroplast membrane translocon complex (TIC) which associates with the outer chloroplast membrane translocon complex (TOC) and forms a supercomplex involved in protein precursor import into the chloroplast stroma (By similarity). Required for the regulation of starch granule size in amyloplasts (PubMed:24335509). Part of the TIC complex, which can interact with components of the TOC complex to form a larger import complex. Highly expressed in third leaf and developing seeds (PubMed:24335509). Expressed in anthers, pistils, flag leaves and young panicles (PubMed:24335509). Belongs to the TamB family. Truncated N-terminus.