▁protect ▁from ▁vir al ▁in fe ctions . ▁These ▁en zym es , ▁when ▁mis reg ulated , ▁are ▁a ▁major ▁source ▁of ▁mut ation ▁in ▁numerous ▁cancer ▁types . ▁ ▁A ▁ 2 0 1 3 ▁review ▁discussed ▁the ▁struct ural ▁and ▁bi oph ys ical ▁aspects ▁of ▁AP OB EC 3 ▁family ▁en zym es . ▁Much ▁of ▁the ▁AP OB EC ▁protein ▁features ▁are ▁described ▁in ▁the ▁widely ▁studied ▁AP OB EC 3 G ' s ▁page . ▁ ▁Family ▁members ▁ ▁Human ▁gen es ▁encoding ▁members ▁of ▁the ▁AP OB EC ▁protein ▁family ▁include : ▁ ▁AP OB EC 1 ▁ ▁AP OB EC 2 ▁ ▁AP OB EC 3 A ▁ ▁AP OB EC 3 B ▁ ▁AP OB EC 3 C ▁ ▁AP OB EC 3 D ▁(" AP OB EC 3 E " ▁now ▁refers ▁to ▁this ) ▁ ▁AP OB EC 3 F ▁ ▁AP OB EC 3 G ▁ ▁AP OB EC 3 H ▁ ▁AP OB EC 4 ▁ ▁Activ ation - indu ced ▁( cy tid ine ) ▁de amin ase ▁( A ID ) ▁ ▁References ▁▁ ▁Category : EC ▁ 3 . 5 . 4 <0x0A> </s> ▁Nicholas ▁Ro yle ▁( born ▁ 2 0 ▁March ▁ 1 9 6 3 ▁in ▁Manchester ) ▁is ▁an ▁English ▁novel ist , ▁editor , ▁publish er , ▁literary ▁rev iewer ▁and ▁cre ative ▁writing ▁lect urer . ▁ ▁Liter ary ▁career ▁ ▁Author ▁Ro yle ▁has ▁written ▁seven ▁nov els : ▁C