AU-1421 is a potassium ion (K⁺) site-directed regulator that specifically acts on various cation transport ATPases. AU-1421 can distinguish between two different K⁺-sensitive phosphorylation intermediate (E2P) states: for non-K⁺ transport type ATPases (such as the sarcoplasmic reticulum Ca²⁺-ATPase), after binding to AU-1421, it mimics the agonistic effect of K⁺, significantly accelerating the hydrolysis (dephosphorylation) of E2P. For K⁺ transport type ATPases (such as the gastric mucosa H⁺/K⁺-ATPase and the renal Na⁺/K⁺-ATPase), after binding to AU-1421, it inhibits the hydrolysis of E2P, stabilizing the phosphorylated intermediate, thereby blocking the ion transport cycle. AU-1421 can be used to study the mechanism of the potassium ion pump.
