InterPro domain: IPR005692

Chloroplast function requires the import of nuclear encoded proteins from the cytoplasm across the chloroplast double membrane. This is accompished by two protein complexes, the Toc complex located at the outer membrane and the Tic complex loacted at the inner membrane [ 1 ]. The Toc complex recognises specific proteins by a cleavable N-terminal sequence and is primarily responsible for translocation through the outer membrane, while the Tic complex translocates the protein through the inner membrane.

This entry represents Tic22, a core member of the Tic complex. Tic22 is a soluble protein and the only Tic complex component of the intermembrane space that has been shown to interact with preproteins during import. It may also act as a chaperone that prevent misfolding or missorting of the preprotein to the intermembrane space and potentially serve as a component that links the Toc and Tic complexes [ 2 ].

1. Molecular biology of chloroplast biogenesis: gene expression, protein import and intraorganellar sorting. Cell. Mol. Life Sci. 58, 420-33
2. New insights into the mechanism of chloroplast protein import and its integration with protein quality control, organelle biogenesis and development. J. Mol. Biol. 427, 1038-1060