Specific high-affinity binding protein for human corticotropin-releasing hormone in normal human plasma.
A protein of Mr 25-40 kilodaltons in normal human plasma binds human corticotropin-releasing hormone (hCRH), but not ovine CRH. Binding requires both N- and C-terminal hCRH sequences and has a Kd of 2 X 10(-10) M and a binding site concentration of 1.4 pmoles per ml of plasma. Its binding is not affected by heating to 56 degrees C for 1 h, but is abolished by exposure to 6 M guanidine-HCl, 10 mM dithiothreitol. Binding proceeds rapidly at 37 degrees C and is 75% complete within 4 min. Neither rat nor sheep plasma appears to contain a CRH-binding protein. CRH-binding protein may explain the brief biological action of hCRH as compared to ovine CRH in man and why high concentrations of plasma immunoreactive hCRH in women during third-trimester pregnancy do not cause increased ACTH secretion.
D000918:Antibody Specificity; D001665:Binding Sites; D001798:Blood Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000097:blood*; D003346:Corticotropin-Releasing Hormone / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D011863:Radioimmunoassay
D001798:Blood Proteins; D002352:Carrier Proteins; D003346:Corticotropin-Releasing Hormone