Ovaj enzim je specifičan za Ca2+-kalmodulin kod kičmenjaka.
Reference
^Jennissen, H.P. & Laub, M. (1988). „Ubiquitin-calmodulin conjugating activity from cardiac muscle”. Biol. Chem. Hoppe-Seyler. 369: 1325—1330. PMID2853950.
^Ziegenhagen, R. & Jennissen, H.P. (1988). „Multiple ubiquitination of vertebrate calmodulin by reticulocyte lysate and inhibition of calmodulin conjugation by phosphorylase kinase”. Biol. Chem. Hoppe-Seyler. 369: 1317—1324. PMID2853949.