This family includes subunit CCB3 of cofactor assembly complex C, involved in c-type cytochrome maturation in photosynthetic organisms [1]. This family also includes uncharacterised protein YggT, associated with bacteria outside the cyanobacteria.

1: A novel pathway of cytochrome c biogenesis is involved in the assembly of the cytochrome b6f complex in arabidopsis chloroplasts. Lezhneva L, Kuras R, Ephritikhine G, de Vitry C; J Biol Chem. 2008;283:24608-24616. PMID:18593701