Background: Inward-rectifier potassium (Kir) channels conduct K+ ions most efficiently into the cell, which are expressed in a wide variety of cells and involved in many physiological processes.The function of Kir channels depends on their gating kinetics induced by phosphatidylinositol 4,5-bisphosphate (PIP2), which is determined by intrinsic conformational features.The mutation of the conservative site between Leu and Ile which locate in the CD loop regulates Kir gating kinetics, but corresponding structural bases remains unclear.