Which one of the following proteins is responsible for the permeability of $$Mg^{2+}$$​ through the tight junctions of tubular cells in the thick ascending limb of Henle?

Correct option is C

Tight junctions in epithelial cells regulate paracellular transport (movement of ions and water between cells).
-In the thick ascending limb of Henle (TAL), reabsorption of Mg²⁺ and Ca²⁺ occurs primarily via the
paracellular pathway.
-Claudin family proteins are essential components of tight junctions that determine selective ion permeability:
-Claudin-16 (also known as paracellin-1) is specifically responsible for Mg²⁺ and Ca²⁺ permeability in the
TAL.
-Mutations in the Claudin-16 gene cause familial hypomagnesemia with hypercalciuria and
nephrocalcinosis (FHHNC).
-ZO proteins (ZO-1, ZO-3) are scaffolding proteins that link tight junction components to the cytoskeleton but do
not directly determine ion selectivity