Glyceraldehyde 3-phosphate dehydrogenase serves as an accessory protein of the cardiac sarcolemmal K(ATP) channel.
Cardiac sarcolemmal ATP-sensitive K+ (K(ATP)) channels, composed of Kir6.2 and SUR2A subunits, are regulated by intracellular ATP and they couple the metabolic status of the cell with the membrane excitability. On the basis of previous studies, we have suggested that glyceraldehyde 3-phosphate dehydrogenase (GAPDH) may be a part of the sarcolemmal K(ATP)-channel protein complex. A polypeptide of approximately 42 kDa was immunoprecipitated with an anti-SUR2A antibody from guinea-pig cardiac membrane fraction and identified as GAPDH. Immunoprecipitation/western blotting analysis with anti-Kir6.2, anti-SUR2A and anti-GAPDH antibodies showed that GAPDH is a part of the sarcolemmal K(ATP)-channel protein complex in vivo. Further studies with immunoprecipitation/western blotting and the membrane yeast two-hybrid system showed that GAPDH associates physically with the Kir6.2 but not the SUR2A subunit. Patch-clamp electrophysiology showed that GAPDH regulates K(ATP)-channel activity irrespective of high intracellular ATP, by producing 1,3-bisphosphoglycerate, a K(ATP)-channel opener. These results suggest that GAPDH is an integral part of the sarcolemmal K(ATP)-channel protein complex, where it couples glycolysis with the K(ATP)-channel activity.
Jovanović
Sofija
S
Maternal and Child Health Sciences, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, UK.
Du
Qingyou
Q
Crawford
Russell M
RM
Budas
Grant R
GR
Stagljar
Igor
I
Jovanović
Aleksandar
A
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D017931:DNA Primers; D004163:Diphosphoglyceric Acids / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism*; D006168:Guinea Pigs; D006801:Humans; D047468:Immunoprecipitation; D032383:Myocytes, Cardiac / Q000201:enzymology*; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments; D015221:Potassium Channels / Q000378:metabolism*; D012394:Rosaniline Dyes; D012508:Sarcolemma / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D020798:Two-Hybrid System Techniques
D017931:DNA Primers; D004163:Diphosphoglyceric Acids; D010446:Peptide Fragments; D015221:Potassium Channels; D012394:Rosaniline Dyes; C068142:glyceraldehyde 3-phosphate dehydrogenase (304-313); C015891:glycerate 1,3-biphosphate; C048139:Coomassie blue; D000255:Adenosine Triphosphate; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases