InterPro domain: IPR023222

This superfamily represents a four helix up-down bundle domain found in a number of proteins including PsbQ from chloroplast and cyanobacterial photosystem II, and cyclocphilins involved in the assembly and maintenanace of phtosystem II [ 1 , 2 , 3 ].

1. The 1.49 A resolution crystal structure of PsbQ from photosystem II of Spinacia oleracea reveals a PPII structure in the N-terminal region. J. Mol. Biol. 350, 1051-60
2. Crystal structure of PsbQ from Synechocystis sp. PCC 6803 at 1.8 A: implications for binding and function in cyanobacterial photosystem II. Biochemistry 49, 2765-7
3. A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in Arabidopsis thaliana. Proc. Natl. Acad. Sci. U.S.A. 104, 15947-52