Chloride/bicarbonate exchanger. Mediates the efficient absorption of chloride ions in the colon, participating in fluid homeostasis. Plays a role in the chloride and bicarbonate homeostasis during sperm epididymal maturation and capacitation. Interacts with PDZK1 (By similarity). Interacts with CFTR, SLC26A6 and SLC9A3R1. Localized in sperm membranes. Midpiece of sperm tail. Colocalizes with CFTR at the midpiece of sperm tail. Expressed in spermatogenic cells. N-glycosylation is required for efficient cell surface expression, and protection from proteolytic degradation. Belongs to the SLC26A/SulP transporter (TC 2.A.53) family.