Background and purpose
The detailed molecular modulation of inward rectifier potassium channels (including the K(IR) 2.3 channel) is not fully understood. The present study was designed to determine whether human K(IR) 2.3 (K(IR) 2.3) channels were regulated by protein tyrosine kinases (PTKs). Experimental approach: Whole-cell patch voltage-clamp, immunoprecipitation, Western blot analysis and site-directed mutagenesis were employed to determine the potential PTK phosphorylation of Kir2.3 current in HEK 293 cells stably expressing Kir2.3 gene. Key
Purpose
The detailed molecular modulation of inward rectifier potassium channels (including the K(IR) 2.3 channel) is not fully understood. The present study was designed to determine whether human K(IR) 2.3 (K(IR) 2.3) channels were regulated by protein tyrosine kinases (PTKs). Experimental approach: Whole-cell patch voltage-clamp, immunoprecipitation, Western blot analysis and site-directed mutagenesis were employed to determine the potential PTK phosphorylation of Kir2.3 current in HEK 293 cells stably expressing Kir2.3 gene. Key
Results
The broad-spectrum PTK inhibitor genistein (10 µM) and the selective epidermal growth factor (EGF) kinase inhibitor AG556 (10 µM) reversibly decreased K(IR) 2.3 current and the effect was reversed by the protein tyrosine phosphatase inhibitor, orthovanadate (1 mM). Although EGF (100 ng·mL(-1) ) and orthovanadate enhanced K(IR) 2.3 current, this effect was antagonized by AG556. However, the Src-family tyrosine kinase inhibitor PP2 (10 µM) did not inhibit K(IR) 2.3 current. Tyrosine phosphorylation of K(IR) 2.3 channels was decreased by genistein or AG556, and was increased by EGF or orthovanadate. The decrease of tyrosine phosphorylation of K(IR) 2.3 channels by genistein or AG556 was reversed by orthovanadate or EGF. Interestingly, the response of K(IR) 2.3 channels to EGF or AG556 was lost in the K(IR) 2.3 Y234A mutant channel.