Archaebacterial chaperonin-mediated protein stabilization

摘要

TF55 is a homooligomeric complex of two stacked rings, closely resembling the quaternary structure of the chaperonins, groEL, hsp60, and RUBISCO-binding protein. Most rings of TF55 contain 9 radially arranged members. The TF55 complex binds unfolded polypeptides in vitro, preventing aggregation at elevated temperature, and exhibits ATPase activity, features consistent with its function as a molecular chaperone. At the level of primary structure, TF55 is not significantly related to the chaperonins but is highly homologous (36-40% identity) to a ubiquitous eukaryotic protein, t complex polypeptide 1 (PCT1).