FunctionElectroneutral exchange of protons for Na(+) and K(+) across the early and recycling endosome membranes. Contributes to calcium homeostasis.
Tissue specificityUbiquitous; but is most abundant in mitochondrion-rich tissues such as brain, skeletal muscle and heart.
Involvement in diseaseDefects in SLC9A6 are the cause of mental retardation syndromic X-linked Christianson type (MRXSC) [MIM:300243]; also known as MRXS-Christianson or X-linked Angelman-like syndrome. The phenotype is characterized by profound mental retardation, epilepsy, ataxia, and microcephaly, and showed phenotypic overlap with Angelman syndrome.
Sequence similaritiesBelongs to the monovalent cation:proton antiporter 1 (CPA1) transporter (TC 2.A.36) family.
Cellular localizationEndosome membrane. Is present in the recycling compartments including early and recycling endosomes, and only appears transiently on the plasma membrane.