APOBEC-2, a cardiac- and skeletal muscle-specific member of the cytidine deaminase supergene family

Biochem Biophys Res Commun. 1999 Jul 5;260(2):398-404. doi: 10.1006/bbrc.1999.0925.


APOBEC-1, which mediates the editing of apolipoprotein (apo) B mRNA, is the only known member of the C (cytidine)-->U (uridine) editing enzyme subfamily of the cytidine deaminase supergene family. Here we report the cloning of APOBEC-2, another member of the subfamily. Human and mouse APOBEC-2 both contain 224 amino acid residues, and their genes are mapped to syntenic regions of human chromosome 6 (6p21) and mouse chromosome 17. By phylogenetic analysis, APOBEC-2 is shown to be evolutionarily related to APOBEC-1, and analysis of substitution rates indicates that APOBEC-2 is a much better conserved gene than APOBEC-1. APOBEC-2 mRNA and protein are expressed exclusively in heart and skeletal muscle. APOBEC-2 does not display detectable apoB mRNA editing activity. Like other editing enzymes of the cytidine deaminase superfamily, APOBEC-2 has low, but definite, intrinsic cytidine deaminase activity. The identification of APOBEC-2 indicates that APOBEC-1 is not the only member of the C-->U editing enzyme subfamily, which, like the A (adenosine)-->I (inosine) subfamily of editing enzymes, must encompass at least two and possibly more different deaminase enzymes. It suggests that the C-->U editing affecting apoB mRNA and other RNAs is not an isolated event mediated by a single enzyme but involves multiple related proteins that have evolved from a primordial gene closely related to the housekeeping enzyme cytidine deaminase.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • APOBEC Deaminases
  • Amino Acid Sequence
  • Animals
  • Cell Line
  • Chromosome Mapping
  • Chromosomes, Human, Pair 6
  • Cytidine Deaminase / chemistry
  • Cytidine Deaminase / genetics*
  • Humans
  • Mice
  • Molecular Sequence Data
  • Multigene Family*
  • Muscle Proteins*
  • Muscle, Skeletal / enzymology*
  • Myocardium / enzymology*
  • Phylogeny
  • Polymerase Chain Reaction
  • RNA Editing*
  • RNA, Messenger / genetics
  • Sequence Homology, Amino Acid


  • Muscle Proteins
  • RNA, Messenger
  • APOBEC Deaminases
  • APOBEC2 protein, human
  • Apobec2 protein, mouse
  • Cytidine Deaminase

Associated data

  • GENBANK/AF161698
  • GENBANK/AF161699