Functions as a beta-subunit for CLCNKA and CLCNKB chloride channels. In the kidney CLCNK/BSND heteromers mediate chloride reabsorption by facilitating its basolateral efflux. In the stria, CLCNK/BSND channels drive potassium secretion by recycling chloride for the basolateral SLC12A2 cotransporter. Interacts with CLCNK channels. Forms probably heteromers with CLCNKA and CLCNKB. Staining in membranes of the renal tubule and of potassium-secreting epithelia of the inner ear is basolateral. Expressed along the distal nephron. Regulated in parallel with CLCNKA under furosemide treatment. A significant decrease occurred after furosemide treatment in inner medulla (0.5 fold), whereas cortical and outer medulla levels remained unaffected. Regulation with CLCNKA in inner medulla is limited to the thin limb; levels in collecting ducts were not affected by furosemide treatment. During furosemide treatment selective down-regulation with CLCNKA in thin limb plays a role in maintaining salt and water homeostasis. Palmitoylation is necessary for activation of plasma membrane-inserted CLC-K/barttin channels.