Review Article

Biology of the KCNQ1 Potassium Channel

Figure 8

Mechanisms of KCNQ1 internalization and recycling. (a) In cardiac myocytes, KCNQ1-KCNE1 complexes can be internalized and recycled by Rab-dependent pathways, with SGK1 stimulating RAB11-dependent recycling in response to stress. channels formed with loss-of-function LQTS mutant D76N-KCNE1 are degraded via a RAB7-dependent pathway [144, 145]. (b) Also in cardiac myocytes, PKC can stimulate KCNE1-dependent clathrin-mediated endocytosis of KCNQ1-KCNE1 , whereas homomeric KCNQ1 is not internalized by this pathway . This process could favor accumulation of non-KCNE1 channels containing KCNQ1 , perhaps in complexes with other KCNE subunits [146, 147]. (c) In the colon, Nedd4.2 (in response to estrogen) stimulates KCNQ1 internalization, leaving KCNE3 at the cell surface. KCNQ1 can be recycled by rapid (Rab4-dependent) or slow (Rab11-dependent) pathways [148].
237431.fig.008