Given below are a few ion transport proteins present on the membrane of pancreatic duct cells.

A. Cystic fibrosis transmembrane conductance regulator (CFTR)
B. Sodium-bicarbonate cotransporter (NBC)
C. K⁺ channel
D. Cl⁻/HCO₃⁻ exchanger

Which one of the following options represents the correct combinations of proteins located on the basolateral membrane of pancreatic duct cells?

Correct option is B

The correct option is (b)

EXPLANATION-

Pancreatic duct cells are polarized epithelial cells with two distinct membrane domains:
                                                      Apical membrane facing the duct lumen
                                                      Basolateral membrane facing the blood/interstitial fluid

(A) CFTR  is primarily located on the apical membrane, where it functions as a chloride channel essential for chloride and bicarbonate secretion into the duct lumen.

(B) Sodium-bicarbonate cotransporter (NBC)  is located on the basolateral membrane and mediates the uptake of bicarbonate ions into the duct cells from the blood side, working together with sodium ions. This cotransporter is crucial for bicarbonate secretion into the pancreatic duct.

(C) K⁺ channels   are also present on the basolateral membrane and help maintain the membrane potential by allowing potassium ions to flow, which supports ion transport and cell volume regulation.

(D) ​Cl⁻/HCO₃⁻ exchanger is usually found on the apical membrane where it participates in bicarbonate secretion by exchanging chloride ions from the duct lumen for bicarbonate ions from the cells.

Thus, the correct answer is: Option (b) : B and C