This family consists of the photosystem II reaction centre protein PsbJ from plants and Cyanobacteria. In Synechocystis sp. PCC 6803 PsbJ regulates the number of photosystem II centres in thylakoid membranes, it is a predicted 4kDa protein with one membrane spanning domain.
Jiyao W et al.(2023). "The conserved domain database in 2023.",