DNA deaminase (cytidine deaminase) which acts as an inhibitor of retrovirus replication and retrotransposon mobility via deaminase-dependent and -independent mechanisms. Selectively targets single-stranded DNA and does not deaminate double-stranded DNA or single- or double-stranded RNA. a 2'-deoxycytidine in single-stranded DNA + H(+) + H2O = a 2'-deoxyuridine in single-stranded DNA + NH4(+) Homodimer. The CMP/dCMP deaminase domain 1 confers deoxycytidine deaminase activity, whereas the CMP/dCMP deaminase domain 2 mediates RNA-dependent oligomerization and virion incorporation. Probable human APOBEC3G ortholog. Belongs to the cytidine and deoxycytidylate deaminase family.