TCP-1 (CTT or eukaryotic type II) chaperonin family, gamma subunit. Chaperonins are involved in productive folding of proteins. They share a common general morphology, a double toroid of 2 stacked rings. In contrast to bacterial group I chaperonins (GroEL), each ring of the eukaryotic cytosolic chaperonin (CTT) consists of eight different, but homologous subunits. Their common function is to sequester nonnative proteins inside their central cavity and promote folding by using energy derived from ATP hydrolysis. The best studied in vivo substrates of CTT are actin and tubulin.