ATP4B

The protein encoded by this gene belongs to a family of P-type cation-transporting ATPases. The gastric H+, K+-ATPase is a heterodimer consisting of a high molecular weight catalytic alpha subunit and a smaller but heavily glycosylated beta subunit. This enzyme is a proton pump that catalyzes the hydrolysis of ATP coupled with the exchange of H(+) and K(+) ions across the plasma membrane. It is also responsible for gastric acid secretion. This gene encodes the beta subunit of the gastric H+, K+-ATPase. [provided by RefSeq]

Full Name

ATPase, H+/K+ exchanging, beta polypeptide

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).

Biological Process

Cell adhesion Source: UniProtKB-KW
Cellular potassium ion homeostasis Source: GO_Central
Cellular sodium ion homeostasis Source: GO_Central
Ion transmembrane transport Source: Reactome
pH reduction Source: Ensembl
Potassium ion import across plasma membrane Source: GO_Central
Response to lipopolysaccharide Source: Ensembl
Response to organonitrogen compound Source: Ensembl
Sodium ion export across plasma membrane Source: GO_Central

Cellular Location

Apical cell membrane; Cell membrane. Localized in the apical canalicular membrane of parietal cells.

Topology

Cytoplasmic: 1-36 aa
Helical: 37-57 aa
Extracellular: 58-291 aa

PTM

N-glycosylation is necessary for assembly and functional expression of the pump at the plasma membrane.