The chaperonin containing TCP1 (MIM 186980) complex (CCT), also called the TCP1 ring complex, consists of 2 back-to-back rings, each containing 8 unique but homologous subunits, such as CCT4. CCT assists the folding of newly translated polypeptide substrates through multiple rounds of ATP-driven release and rebinding of partially folded intermediate forms. Substrates of CCT include the cytoskeletal proteins actin (see MIM 102560) and tubulin (see MIM 191130), as well as alpha-transducin (MIM 139330) (Won et al., 1998 [PubMed 9819444]).[supplied by OMIM, Mar 2008].