passages.id: split_4_test_3110_passage
passages.type: progene_text
passages.text: We conclude that AID and APOBEC2 are likely to be the ancestral members of the AID / APOBEC family ( going back to the beginning of vertebrate speciation ) with both APOBEC1 and APOBEC3 being mammal - specific derivatives of AID and a complex set of domain shuffling underpinning the expansion and evolution of the primate APOBEC3s .