This family includes includes Protein CHLORORESPIRATORY REDUCTION 42 (CRR42) from Arabidopsis thaliana, which is required for both formation and activity of the chloroplast NAD(P)H dehydrogenase (NDH) complex of the photosynthetic electron transport chain [1]. CRR42 functions in assembly or stabilization of the NDH complex and it is likely involved, together with CRR1 and CRR6 in the incorporation of NdhJ, NdhM, NdhK and NdhI into the NDH subcomplex A assembly intermediate (NAI500) to produce the complex NAI400 [1]. This family also includes uncharacterised proteins from cyanobacteria.

1: Multistep assembly of chloroplast NADH dehydrogenase-like subcomplex A requires several nucleus-encoded proteins, including CRR41 and CRR42, in Arabidopsis. Peng L, Fukao Y, Fujiwara M, Shikanai T; Plant Cell. 2012;24:202-214. PMID:22274627