Component of the chaperonin-containing T-complex (TRiC), a molecular chaperone complex that assists the folding of proteins upon ATP hydrolysis. The TRiC complex mediates the folding of WRAP53/TCAB1, thereby regulating telomere maintenance. As part of the TRiC complex may play a role in the assembly of BBSome, a complex involved in ciliogenesis regulating transports vesicles to the cilia. The TRiC complex plays a role in the folding of actin and tubulin. Component of the chaperonin-containing T-complex (TRiC), a heterooligomeric complex of about 850 to 900 kDa that forms two stacked rings, 12 to 16 nm in diameter. Interacts with PACRG (By similarity). Interacts with DNAAF4 (By similarity). Interacts with DLEC1 (By similarity). Defects in Cct4 are a cause of an early onset sensory neuropathy knowm as mutilated foot (mf). The main clinical features include ataxia, insensitivity to pain and foot ulceration. The pathological features include a severe reduction in the number of sensory ganglia and fibers. Belongs to the TCP-1 chaperonin family.