Phospholipid-transporting ATPase IK (also known as ATP8B3 orATP1K) belongs to the subfamily IV of the P-type ATPases family, whose members transport phospholipids across the membrane. The function of ATP8B3 is not clear. Unlike other type IV members (ATP8B1,2,4), ATP8B3 does not seem to interact with either CDC50A or CDC50B []. 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 []. However, the disruption of ATP8B3 in mice does not affect sperm morphology or fertilisation rate [].
