This family consists of various photosystem II 4 kDa reaction centre components (PsbK) from plant and Cyanobacteria. The photosystem II reaction centre is responsible for catalysing the core photosynthesis reaction the light-induced splitting of water and the consequential release of dioxygen. In C. reinhardtii the psbK product is required for the stable assembly and/or stability of the photosystem II complex [1].

1: Directed disruption of the Chlamydomonas chloroplast psbK gene destabilizes the photosystem II reaction center complex. Takahashi Y, Matsumoto H, Goldschmidt-Clermont M, Rochaix JD; Plant Mol Biol 1994;24:779-788. PMID:8193302