Chaperone protein involved in the assembly of the mitochondrial NADH:ubiquinone oxidoreductase complex (complex I). Required for normal growth and reproduction. RNAi-mediated knockdown impairs mitochondrial complex I assembly. Reduced body size, reduced fat content, fewer embryos and an extended egg laying period. These phenotypes are exacerbated when nuaf-3 is simultaneously knocked down. Belongs to the CIA30 family.