Regulation of ROMK channels by protein tyrosine kinase and tyrosine phosphatase

Renal outer medulla K (ROMK) channels play an important role in K recycling in the thick ascending limb and in K secretion in the cortical collecting duct. ROMK1, a member of the ROMK family, has been shown to be a substrate for protein tyrosine kinase (PTK). The tyrosine phosphorylation of ROMK channels increases with low dietary K intake and decreases with high dietary K intake. Moreover, the stimulation of tyrosine phosphorylation of ROMK1 channels decreases the number of K channels by facilitating endocytosis. In contrast, the stimulation of tyrosine dephosphorylation increases the number of ROMK1 channels in the cell membrane by enhancing membrane insertion. PTK and tyrosine phosphatase-induced regulation of ROMK1 channels play a key role ill mediating the effect of the dietary K intake on renal K secretion. (C) 2002, Elsevier Science Inc.