Isolation of neonatal cardiomyocytes reduces the expression of the GTP-binding protein, Gh.
alpha 1-Adrenoceptors in most tissues couple with the heterotrimeric GTP-binding protein Gq, the alpha subunit of which activates the beta-isoforms of phospholipase C. However, in heart (and in liver) alpha 1-adrenoceptors have been reported to couple to a high molecular weight GTP-binding protein. Gh, which functions both as a type II transglutaminase and as a receptor coupling protein. Gh activates a phospholipase isoform distinct from phospholipase C-beta. Here we report that isolation and culture of neonatal cardiomyocytes decreased the expression of Gh without reducing the content of Gq or Gi. Gh was readily detected in extracts from intact neonatal and adult heart tissues. The expression of Gh thus appears to be a feature of intact cardiac tissue.
Vincan
E
E
Cellular Biochemistry Laboratory, Baker Medical Research Institute, Melbourne, Victoria, Australia.
Neylon
C B
CB
Graham
R M
RM
Woodcock
E A
EA
D000367:Age Factors; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004789:Enzyme Activation; D004790:Enzyme Induction; D019204:GTP-Binding Proteins / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics; D005786:Gene Expression Regulation; D006321:Heart / Q000254:growth & development; D007527:Isoenzymes / Q000378:metabolism; D008969:Molecular Sequence Data; D009206:Myocardium / Q000166:cytology*; D010740:Phospholipases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism; D015398:Signal Transduction; D011503:Transglutaminases / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics
D007527:Isoenzymes; D018340:Receptors, Adrenergic, alpha-1; D011503:Transglutaminases; D010740:Phospholipases; D019204:GTP-Binding Proteins