Identification and molecular characterization of a high-affinity cardiomyocyte transforming growth factor-beta 2 receptor.
Rat neonatal heart muscle cells (cardiomyocytes) were found to express a high-affinity surface receptor for transforming growth factor-beta 2 (TGF-beta 2). Specific binding was rapid, saturable, ligand-selective, and reversible. Equilibrium binding analyses revealed that the cardiomyocyte had one class of specific binding sites with a Kd < or = 26 pM TGF-beta 2, a Bmax of approximately 9 fmol/10(6) cells, and approximately 5,000 binding sites/cardiomyocyte. Binding was selective for TGF-beta 2 in comparison to other TGF-beta isoforms and to unrelated growth factors. Affinity-binding experiments revealed three types of cardiomyocyte TGF-beta 2 binding proteins, the most prominent of which corresponded to the high-molecular mass proteoglycan. These data raise the possibility that the anti-ischemic cardioprotective effects of TGF-beta may reflect receptor-mediated signal transduction at the cardiomyocyte level.
Research Department, CIBA-GEIGY Corp., Summit, NJ 07901.
J
J
Ross
D R
DR
Janero
D
D
Hreniuk
D000345:Affinity Labels; D000818:Animals; D000831:Animals, Newborn; D001667:Binding, Competitive; D007700:Kinetics; D008970:Molecular Weight; D009206:Myocardium / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D000345:Affinity Labels; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta