Required for both formation and activity of the chloroplast NAD(P)H dehydrogenase (NDH) complex of the photosynthetic electron transport chain (PubMed:22274627). Functions in assembly or stabilization of the NDH complex; probably 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 (PubMed:22274627). Biogenesis factor component of the plastidial NDH subcomplex A. Specifically defective in the accumulation of subcomplex A, a stroma-protruding arm of the chloroplast NADH dehydrogenase-like complex (NDH). Truncated N-terminus.