This family consists of several bacterial and plant photosystem II protein Y (PsbY) sequences. PsbY is a manganese-binding protein that has an L-arginine metabolising enzyme activity [1].

1: PsbY, a novel manganese-binding, low-molecular-mass protein associated with photosystem II. Gau AE, Thole HH, Sokolenko A, Altschmied L, Hermann RG, Pistorius EK; Mol Gen Genet 1998;260:56-68. PMID:9829828