This family contains chaperones of the 20S proteasome which function in early 20S proteasome assembly. The structures of two of the proteins in this family (POC3 and POC4) have been solved, and they closely resemble those of the mammalian proteasome assembling chaperone PAC3, although there is little sequence similarity between them [2].

1: 20S proteasome assembly is orchestrated by two distinct pairs of chaperones in yeast and in mammals. Le Tallec B, Barrault MB, Courbeyrette R, Guerois R, Marsolier-Kergoat MC, Peyroche A; Mol Cell. 2007;27:660-674. PMID:17707236

2: Crystal structure of a chaperone complex that contributes to the assembly of yeast 20S proteasomes. Yashiroda H, Mizushima T, Okamoto K, Kameyama T, Hayashi H, Kishimoto T, Niwa S, Kasahara M, Kurimoto E, Sakata E, Takagi K, Suzuki A, Hirano Y, Murata S, Kato K, Yamane T, Tanaka K; Nat Struct Mol Biol. 2008;15:228-236. PMID:18278057