The Effect of Zinc on the Enteral Absorption of Copper. Panel A shows how copper (Cu) is absorbed into the enterocytes from the intestinal lumen by way of a high-affinity Cu transport protein (CTR1) and divalent metal transporter 1 (DMT1). On the apical side, Cu reaches the peripheral circulation through a transporting ATPase (ATP7A). Once inside the cytoplasm of the enterocyte, Cu binds to metallothioneins (MT), proteins that are meant to prevent toxic effects of Cu.9 Panel B shows how zinc (Zn) causes Cu deficiency by increasing MT synthesis in the cytoplasm. When Cu is bound to metallothionein, it is lost in the feces by way of apoptosis of intestinal cells. #Pathophysiology #ZincToxicity #CopperAbsorption #NEJM
