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Calbindin

Vitamin D-induced intracellular calcium-binding protein that facilitates transcellular calcium absorption in the small intestine (9 kDa) and reabsorption in the kidney (28 kDa).

Also: Calbindin-D28k, Calbindin-D9k

Calbindin-D9k in enterocytes binds two Ca2+ per molecule and shuttles them from apical TRPV6 channels to the basolateral PMCA1b pump, preventing free cytosolic Ca2+ from disrupting cell signaling. Its synthesis is induced by 1,25(OH)2D via VDR binding to a vitamin D response element. Calbindin-D28k in the distal nephron and brain binds four Ca2+ per molecule. Both are key effectors of vitamin D's calcemic action.

How one textbook covers it

  • Modern Nutrition in Health and Disease, 12th ed. — Ch 7: Calcium

    Calbindin-D9k in enterocytes binds two Ca2+ per molecule and shuttles them from apical TRPV6 channels to the basolateral PMCA1b pump, preventing free cytosolic Ca2+ from disrupting cell signaling. Its synthesis is induced by 1,25(OH)2D via VDR binding to a vitamin D response element. Calbindin-D28k in the distal nephron and brain binds four Ca2+ per molecule. Both are key effectors of vitamin D's calcemic action.

Related terms

Calcitriol, PMCA, TRPV6, VDR