NKAIN4 (Sodium/potassium-transporting ATPase subunit beta-1-interacting protein 4), also known as FAM77A, is a 208 amino acid mulit-pass membrane protein that exists as multiple alternatively spliced isoforms and interacts with Na+/K+-ATPase ∫1, a subunit of the Na+/K+-ATPase complex. Since it is expressed in the central nervous system and is involved with an essential long-term regulator of membrane potential, it is likely that NKAIN4 is critical for neuronal function.