A mechanism of generating protein diversity is mRNA editing. Members of this family are C-to-U editing enzymes. The N-terminal domain of APOBEC-1 like proteins is the catalytic domain, while the C-terminal domain is a pseudocatalyitc domain. More specifically, the catalytic domain is a zinc dependent deaminases domain and is essential for cytidine deamination.APOBEC-3 like members contain two copies of this domain. RNA editing by APOBEC-1 requires homodimerization and this complex interacts with RNA binding proteins to from the editosome (and references therein). This family also includes the functionally homologous activation induced deaminase (AID), which is essential for the development of antibody diversity in B lymphocytes, and the sea lamprey PmCDA1 and PmCDA2, which are predicted to play an AID-like role in the adaptive immune response of jawless vertebrates. Divergent members of this family are present in various eukaryotes such as Nematostella, C. elegans, Micromonas and Emiliania, and prokaryotes such as Wolbachia and Pseudomonas brassicacearum.