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Structural analogs of atriopeptins (APs) were compared for their ability to activate particulate guanylate cyclase and bind to specific receptors in rat adrenal membranes. All analogs tested increase Vmax without altering the concentration of substrate required for half-maximum activity or the positive coperativity exhibited by the enzyme. Maximum velocities (pmoles of cGMP produced per min per mg protein) achieved in the absence and presence of APs were 128.3 +/- 6.6 and 283.8 +/- 20.6 using Mn2+-GTP, and 53.7 +/- 3.7 and 149.9 +/- 7.6 using Mg2+-GTP as the substrate, respectively. Although all APs were equally efficacious in activating the enzyme, their rank potency was ANF (8-33) = AP III = AP II greater than AP I when either divalent cation was used as the cofactor. The EC50 for activation of guanylate cyclase by AP I was about 10(-7) M, while that for the other peptides was about 10(-8) M, using either divalent cation cofactor. 125I-labeled ANF bound to rat adrenal membranes with a KD of 5.10(-10) M. Although all APs were equally efficacious in competing with labeled ANF for receptor binding, their rank potency was identical to that for enzyme activation. The Ki for AP I was about 10(-8) M, while that for the other peptides was about 10(-10) M. These data suggest that the carboxy terminal Phe-Arg present in the AP analogs except AP I and critical for biological and receptor-binding activity are also important in coupling receptor-ligand interaction with guanylate cyclase activation. The correlation between the rank order potency for receptor binding, enzyme activation, and the reported physiological actions of APs support the suggestion of a functional coupling between these proteins.
S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
January 1989,
The International journal of biochemistry,
S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
June 2011,
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S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
October 1989,
Molecular and cellular biochemistry,
S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
January 2012,
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S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
July 1998,
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S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
November 1996,
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S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
March 1991,
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S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
July 1988,
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S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
May 1992,
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S A Waldman, and
R M Rapoport, and
R R Fiscus, and
D C Leitman, and
L Y Chang, and
F Murad
January 1994,
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