Members of this family are probable integral membrane proteins. Their molecular function is unknown. CemA proteins are found in the inner envelope membrane of chloroplasts but not in the thylakoid membrane [1]. A cyanobacterial member of this family has been implicated in CO2 transport, but is probably not a CO2 transporter itself [1]. They are predicted to be haem-binding however this has not been proven experimentally [2].

1: cemA homologue essential to CO2 transport in the cyanobacterium Synechocystis PCC6803. Katoh A, Lee KS, Fukuzawa H, Ohyama K, Ogawa T; Proc Natl Acad Sci U S A 1996;93:4006-4010. PMID:8633006

2: An open reading frame encoding a putative haem-binding polypeptide is cotranscribed with the pea chloroplast gene for apocytochrome f. Willey DL, Gray JC; Plant Mol Biol 1990;15:347-356. PMID:2103453