2.A.36.2.3
solute carrier family 9, subfamily B, SLC9B. (NHA1, cation proton antiporter 1). The SLC9 gene family encodes Na⁺/H⁺ exchangers (NHEs), a group of membrane transport proteins critically involved in the regulation of cytoplasmic and organellar pH, cell volume, as well as systemic acid-base and volume homeostasis (Anderegg et al. 2022). NHEs of the SLC9A subfamily (NHE 1-9) are well-known for their roles in human physiology and disease. Much less is known about the two members of the SLC9B subfamily, NHA1 and NHA2, which share higher similarity to prokaryotic NHEs than the SLC9A paralogs. NHA2 (also known as SLC9B2) is ubiquitously expressed and participates in renal blood pressure and electrolyte regulation, insulin secretion and systemic glucose homeostasis.  NHA2 may contribute to the pathogenesis of polycystic kidney disease. NHA1 (also known as SLC9B1) is mainly expressed in testis and is important for sperm motility and thus male fertility. Anderegg et al. 2022 presented a summary of the structure, function and regulation of expression of the SLC9B subfamily members, focusing primarily on the better-studied SLC9B paralog, NHA2.