CESK1, also known as CCT8L2 (chaperonin containing TCP1, subunit 8 theta-like 2), is a 557 amino acid protein that localizes to the cytoplasm and is thought to function as a molecular chaperone, possibly assisting protein folding after ATP hydrolysis. CESK1 belongs to the TCP-1 chaperonin family and is encoded by a gene which maps to human chromosome 22. Mutations in several of the genes that map to chromosome 22 are involved in the development of Phelan-McDermid syndrome, neurofibromatosis type 2, autism and schizophrenia. Additionally, translocations between chromosomes 9 and 22 may lead to the formation of the Philadelphia chromosome and the subsequent production of the novel fusion protein Bcr-Abl, a potent cell proliferation activator found in several types of leukemias.