Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 8

Claudin Selectivity. Claudin-4 normally prohibits movement of Na + ions across epithelial cells that express it. However, when positively charged amino acids near the tip of the large extracellular loop of claudin-4 are changed to negatively charged amino acids, Na + can pass through the epithelium. How do you account for this change in permeability to Na +