This family consists of the 33 KDa photosystem II polypeptide from the oxygen evolving complex (OEC) of plants and cyanobacteria. The protein is also known as the manganese-stabilising protein as it is associated with the manganese complex of the OEC and may provide the ligands for the complex [1].

1: Cloning, nucleotide sequence and mutational analysis of the gene encoding the Photosystem II manganese-stabilizing polypeptide of Synechocystis 6803. Philbrick JB, Zilinskas BA; Mol Gen Genet 1988;212:418-425. PMID:3138527