This family contains a domain common to the cobN protein and to magnesium protoporphyrin chelatase. CobN is implicated in the conversion of hydrogenobyrinic acid a,c-diamide to cobyrinic acid [1]. Magnesium protoporphyrin chelatase is involved in chlorophyll biosynthesis [2].

1: Nucleotide sequence and genetic analysis of a 13.1-kilobase-pair Pseudomonas denitrificans DNA fragment containing five cob genes and identification of structural genes encoding Cob(I)alamin adenosyltransferase, cobyric acid synthase, and bifunctional cob Crouzet J, Levy-Schil S, Cameron B, Cauchois L, Rigault S, Rouyez MC, Blanche F, Debussche L, Thibaut D; J Bacteriol 1991;173:6074-6087. PMID:1655697

2: Olive: a key gene required for chlorophyll biosynthesis in Antirrhinum majus. Hudson A, Carpenter R, Doyle S, Coen ES; EMBO J 1993;12:3711-3719. PMID:8404842