Receptor with tyrosine-protein kinase activity. Functions as a pH sensing receptor which is activated by increased extracellular pH. Activates an intracellular signaling pathway that involves IRS1 and AKT1/PKB. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Probable tetramer of 2 alpha and 2 beta chains linked by disulfide bonds. The alpha chains contribute to the formation of the ligand-binding domain, while the beta chains carry the kinase domain (By similarity). Expressed preferentially in the kidney. Also found in stomach and thymus but not in skeletal muscle, brain, intestine, and uterus. The extracellular domain is required for sensing alterations in external pH. Autophosphorylated on tyrosine residues between pH 7.9 and pH 10.5. Belongs to the protein kinase superfamily. Tyr protein kinase family. Insulin receptor subfamily.