The sodium/hydrogen exchanger 9B1 (SLC9B1 aka Na+/H+ exchanger like domain containing 1, NHEDC1) is specifically expressed on the plasma membrane of the testis and may be implicated in infertility (Ye et al. 2006). Sodium/hydrogen exchanger 9C2 (SLC9C2), also localized to the plasma membrane, may be involved in pH regulation although this protein has not been fully characterized.