Epithelial ion channel that plays an important role in the regulation of epithelial ion and water transport and fluid homeostasis. Mediates the transport of chloride ions across the cell membrane (By similarity). Channel activity is coupled to ATP hydrolysis. The ion channel is also permeable to HCO(3)(-); selectivity depends on the extracellular chloride concentration. Exerts its function also by modulating the activity of other ion channels and transporters. Contributes to the regulation of the pH and the ion content of the epithelial fluid layer (By similarity). ATP + H2O + closed Cl(-) channel = ADP + phosphate + open Cl(-) channel. Monomer; does not require oligomerization for channel activity. May form oligomers in the membrane (By similarity). The channel is internalized from the cell surface into an endosomal recycling compartment, from where it is recycled to the cell membrane. Expressed in the rectal gland (at protein level). Binds and hydrolyzes ATP via the two cytoplasmic ABC transporter nucleotide-binding domains. The two ATP-binding domains interact with each other, forming a head-to-tail dimer. Normal ATPase activity requires interaction between the two domains. The first ABC transporter nucleotide-binding domain has no ATPase activity by itself. The disordered R region mediates channel activation when it is phosphorylated, but not in the absence of phosphorylation. Phosphorylated; cAMP treatment promotes phosphorylation and activates the channel. Dephosphorylation decreases the ATPase activity (in vitro). Phosphorylation at PKA sites activates the channel. Phosphorylation at PKC sites enhances the response to phosphorylation by PKA. Belongs to the ABC transporter superfamily. ABCC family. CFTR transporter (TC 3.A.1.202) subfamily.