8pvr

Structural highlights

Function

SL9A9_HORSE Endosomal Na(+), K(+)/H(+) antiporter. Mediates the electroneutral exchange of endosomal luminal H(+) for a cytosolic Na(+) or K(+) (PubMed:33118634). By facilitating proton efflux, SLC9A9 counteracts the acidity generated by vacuolar (V)-ATPase, thereby limiting luminal acidification. Regulates organellar pH and consequently, endosome maturation and endocytic trafficking of plasma membrane receptors and neurotransporters (By similarity). Promotes the recycling of transferrin receptors back to the cell surface to facilitate additional iron uptake in the brain (By similarity). Regulates synaptic transmission by regulating the luminal pH of axonal endosomes. Regulates phagosome lumenal pH, thus affecting phagosome maturation, and consequently, microbicidal activity in macrophages. Can also be active at the cell surface of specialized cells, e.g., in the inner ear hair bundles uses the high K(+) of the endolymph to regulate intracelular pH (By similarity).[UniProtKB:Q8BZ00][UniProtKB:Q8IVB4]^[1]

References

1. ↑ Winkelmann I, Matsuoka R, Meier PF, Shutin D, Zhang C, Orellana L, Sexton R, Landreh M, Robinson CV, Beckstein O, Drew D. Structure and elevator mechanism of the mammalian sodium/proton exchanger NHE9. EMBO J. 2020 Oct 29:e105908. doi: 10.15252/embj.2020105908. PMID:33118634 doi:http://dx.doi.org/10.15252/embj.2020105908