This is a family of bacterial putative uroporphyrinogen-III C-methyltransferase proteins. It forms one of the members of a complex of proteins involved in the biogenesis of the inner membrane in E.coli. Uroporphorphyrin-III C-methyltransferase (HemX) is a single spanning inner membrane protein that regulates the activity of NAD(P)H:glutamyl-tRNA reductase (HemA) in the tetrapyrrole biosynthesis pathway [1,2].

1: Nucleotide sequence of the hemX gene, the third member of the Uro operon of Escherichia coli K12. Sasarman A, Echelard Y, Letowski J, Tardif D, Drolet M; Nucleic Acids Res. 1988;16:11835. PMID:3062586

2: Protein complexes of the Escherichia coli cell envelope. Stenberg F, Chovanec P, Maslen SL, Robinson CV, Ilag LL, von Heijne G, Daley DO; J Biol Chem. 2005;280:34409-34419. PMID:16079137