title: Identification of a 42K phosphoprotein of platelets modulated by collagen: the alpha-subunit of pyruvate dehydrogenase.
abstract: Platelets exposed to collagen sufficient to stimulate the release reaction show an increase in labeling of two intracellular proteins with molecular weights of 20,000 and 42,000. The 20,000 Mr protein has already been identified as the light chain of myosin whereas the identity of the 42,000 Mr protein had not been established. By use of biochemical and immunological techniques, the identify of the 42,000 Mr component of prelabeled platelets found in the 100,000g supernatant of freeze-thawed or sonicated cells appears to be one of the subunits of pyruvate dehydrogenase complex which is translocated from the mitochondria to the 100,000g supernatant during the preparative procedure. Increased phosphorylation of the 42,000 Mr protein occurred after collagen stimulation and was accompanied by diminished pyruvate dehydrogenase activity.
mesh_terms: D000244:Adenosine Diphosphate / Q000097:blood; D000246:Adenosine Diphosphate Ribose / Q000097:blood; D000255:Adenosine Triphosphate / Q000097:blood; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D002645:Chickens; D003094:Collagen / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007159:Immunologic Tests; D008928:Mitochondria / Q000201:enzymology; D008970:Molecular Weight; D010750:Phosphoproteins / Q000097:blood*; D011768:Pyruvate Dehydrogenase Complex / Q000097:blood*
chemical_list: D010750:Phosphoproteins; D011768:Pyruvate Dehydrogenase Complex; D000246:Adenosine Diphosphate Ribose; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D003094:Collagen