ATP4B
Domain
The C-terminal lobe folds into an immunoglobulin-like domain and mediates cell adhesion properties.
Function
The beta subunit of the gastric H(+)/K(+) ATPase pump which transports H(+) ions in exchange for K(+) ions across the apical membrane of parietal cells. Plays a structural and regulatory role in the assembly and membrane targeting of a functionally active pump (By similarity). Within a transport cycle, the transfer of a H(+) ion across the membrane is coupled to ATP hydrolysis and is associated with a transient phosphorylation of the alpha subunit that shifts the pump conformation from inward-facing (E1) to outward-facing state (E2). Interacts with the phosphorylation domain of the alpha subunit and functions as a ratchet, stabilizing the lumenal-open E2 conformation and preventing the reverse reaction of the transport cycle (By similarity).
Post-translational modifications
N-glycosylation is necessary for assembly and functional expression of the pump at the plasma membrane.
Sequence Similarities
Belongs to the X(+)/potassium ATPases subunit beta family.
Cellular localization
- Apical cell membrane
- Single-pass type II membrane protein
- Cell membrane
- Single-pass type II membrane protein
- Localized in the apical canalicular membrane of parietal cells.
Alternative names
Potassium-transporting ATPase subunit beta, Gastric H(+)/K(+) ATPase subunit beta, Proton pump beta chain, ATP4B