Phospholipid-transporting ATPase FetA (also known as ATP8B5) belongs to the subfamily IV of the P-type ATPases family, whose members transport phospholipids across the membrane. The function of ATP8B5 is not clear. It is exclusively expressed in the testis where it localises to the acrosomes of spermatids, the organelle which develops in the anterior half of the head of spermatozoa []. It may play a role in Golgi morphology and secretory function [].