The ATP8B1 gene encodes a type-4 P-type cation transport ATPase with phospholipid-translocating ATPase activity. Specifically, the ATP8B1 protein translocates phosphatidylserine and phosphatidylethanolamine from the outer to the inner leaflets of membrane bilayers, thus maintaining lipid homeostasis. The ATPase is also involved in the transport of a mitochondrial membrane phospholipid known as cardiolipin. By carrying out its function, ATP8B1 is involved in bile acid and bile salt transport, bile acid metabolic process, regulation of microvillus assembly and vestibulocochlear nerve formation.
The gene is associated with Cholestasis, Benign Recurrent Intrahepatic, 1 (BRIC1), Cholestasis, Progressive Familial Intrahepatic, 1 (PFIC1) and Cholestasis, Intrahepatic, Of Pregnancy, 1 (ICP1). ICP1 is a reversible form of cholestasis occurring in the third trimester of pregnancy. BRIC1 is a relatively mild condition characterized by intermittent episodes of cholestasis accompanied by pruritis and cholestatic jaundice. PFIC1 is a more severe disorder characterized by short stature, deafness, diarrhea and end stage liver disease.