Epithelial ion channel that plays an important role in the regulation of epithelial ion and water transport and fluid homeostasis (PubMed:20933420, PubMed:23487313, PubMed:25592226). 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). Required for normal fluid homeostasis in the gut (PubMed:20933420). Required for normal volume expansion of Kupffer's vesicle during embryonic development and for normal establishment of left-right body patterning (PubMed:23487313, PubMed:26432887). Required for normal resistance to infection by P.aeruginosa strain PA14 and strain SMC573 (PubMed:20732993). ATP + H2O + closed Cl(-) channel = ADP + phosphate + open Cl(-) channel. Monomer; does not require oligomerization for channel activity (By similarity). Interacts with cse1l; this interaction may down-regulate cftr activity (PubMed:20933420). The channel is internalized from the cell surface into an endosomal recycling compartment, from where it is recycled to the cell membrane. Detected in gut epithelium (at protein level) (PubMed:20933420). Detected in kidney, spleen, intestine and liver (PubMed:20732993). Detected in pancreatic duct epithelium at 5 dpf and throughout adult life (PubMed:25592226). First detected in developing pancreatic duct at 3 dpf (PubMed:25592226). Detected on Kupffer's vesicle during embryonic development (PubMed:23487313, PubMed:26432887). Detected on neural floorplate, brain and pronephric duct primordia in embryos at the 10 somite stage (PubMed:26432887). 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; this activates the channel (PubMed:27912062). Dephosphorylation strongly decreases ATPase activity (PubMed:27912062). Phosphorylation at PKA sites activates the channel. Phosphorylation at PKC sites enhances the response to phosphorylation by PKA (By similarity). Considerable lethality around 10 dpf (PubMed:25592226). No effect on initial pancreas development, but at 16 dpf mutants display loss of pancreatic acinar tissue (PubMed:25592226). At 22 dpf, most pancreatic acinar tissue has disappeared and has been replaced by fibrotic tissue that surrounds dilated, mucus-filled ducts (PubMed:25592226). Morpholino knockdown of the protein in 48 hpf embryos leads to impaired resistance to P.aeruginosa strain PA14 and strain SMC573, as shown by the increased bacterial burden, but there is no effect on resistance to E.tarda, B.cenocepacia, S.aureus MZ100, E.coli XL-10 and H.influenzae Hib EAGAN (PubMed:20732993). Morpholino knockdown of the protein causes an important reduction of the volume of Kupffer's vesicle during embryonic development (PubMed:26432887). Mutations that lead to the production of a severely truncated protein that ends before the start of the fourth transmembrane domain disrupt normal left-right body patterning during embryogenesis and abolish lumen expansion of Kupffer's vesicle. Belongs to the ABC transporter superfamily. ABCC family. CFTR transporter (TC 3.A.1.202) subfamily.