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Molecule Parameter List for cAMP

The statistics table lists the distribution of a molecule acting either as a substrate, product, enzyme or as a molecule within the network.
The text color of a molecule is highlighted by color.
Statistics
cAMP participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1002140

Accession and Pathway Details
Accession NameAccession No.Accession TypePathway Link
cAMP_pathway25Network
Shared_Object_cAMP_pathway PKA AC 
Gs 
This is a model of the canonical cAMP signaling pathway:
Ligand->Receptor->G-protein->Cyclase->cAMP->PKA.
It also includes phosphodiesterases to balance out cAMP formation.Bhalla US Methods Enzymol. 2002;345:3-23

cAMP acting as a Molecule in  
cAMP_pathway Network
NameAccession NamePathway NameInitial Conc.
(uM)
Volume
(fL)
Buffered
cAMPcAMP_pathway
Accession No. : 25
  • Shared_Object_
    cAMP_pathway

    Pathway No. : 134
  • 01000No
    Key second messenger.

    cAMP acting as a Substrate for an Enzyme in  
    cAMP_pathway Network
     Enzyme Molecule /
    Enzyme Activity
    Accession NamePathway NameKm (uM)kcat (s^-1)RatioEnzyme TypeReagents
    1cAMP-PDE  /
    PDE
    cAMP_pathway
    Accession No. : 25
    AC
    Pathway No. : 136
    19.8413104explicit E-S complexSubstrate
    cAMP

    Product
    AMP
        Best rates are from Conti et al Biochem 34 7979-7987 1995. Though these are for the Sertoli cell form, it looks like they carry nicely into alternatively spliced brain form. See Sette et al JBC 269:28 18271-18274 Km ~2 uM, Vmax est ~ 10 umol/min/mg for pure form. Brain protein is 93 kD but this was 67. So k3 ~10, k2 ~40, k1 ~4.2e-6
    2cAMP-PDE*  /
    PDE*
    cAMP_pathway
    Accession No. : 25
    AC
    Pathway No. : 136
    19.8413204explicit E-S complexSubstrate
    cAMP

    Product
    AMP
        This form has about twice the activity of the unphosphorylated form. See Sette et al JBC 269:28 18271-18274 1994. We'll ignore cGMP effects for now.

    cAMP acting as a Product of an Enzyme in  
    cAMP_pathway Network
    Enzyme Molecule /
    Enzyme Activity
    Accession NamePathway NameKm (uM)kcat (s^-1)RatioEnzyme TypeReagents
    Gs.AC  /
    cyclase
    cAMP_pathway
    Accession No. : 25
    AC
    Pathway No. : 136
    20184Classical Michaelis-Menten
    V = Etot.S.Kcat/Km+S
    Substrate
    ATP

    Product
    cAMP
    See Feinstein et al PNAS 88:10173-10177, Jacobowitz et al JBC 286(6):3829-3832 Smigel, JBC 261(4):1976-1982 (1986)

    cAMP acting as a Substrate in a reaction in  
    cAMP_pathway Network
    Kd is calculated only for second order reactions, like nA+nB <->nC or nA<->nC+nD, where n is number and A,B,C,D are molecules, where as for first order reactions Keq is calculated. Kd for higher order reaction are not consider.
     NameAccession NamePathway NameKfKbKdtauReagents
    1
  • cAMP-bind-site-B
    1
  • cAMP_pathway
    Accession No. : 25
    PKA
    Pathway No. : 135
    54
    (uM^-1 s^-1)
    33
    (s^-1)
    Kd(bf) = 0.6111(uM)-Substrate
    R2C2
    cAMP

    Product
    cAMP.R2C2
      Hasler et al FASEB J 6:2734-2741 1992 say Kd =1e-7M for type II, 5.6e-8 M for type I. Take mean which comes to 2e-13 #/cell Smith et al PNAS USA 78:3 1591-1595 1981 have better data. First kf/kb=2.1e7/M = 3.5e-5 (#/cell). Ogreid and Doskeland Febs Lett 129:2 287-292 1981 have figs suggesting time course of complete assoc is < 1 min.
    2
  • cAMP-bind-site-B
    2
  • cAMP_pathway
    Accession No. : 25
    PKA
    Pathway No. : 135
    54
    (uM^-1 s^-1)
    33
    (s^-1)
    Kd(bf) = 0.6111(uM)-Substrate
    cAMP
    cAMP.R2C2

    Product
    cAMP2.R2C2
      For now let us set this to the same Km (1e-7M) as site B. This gives kf/kb = .7e-7M * 1e6 / (6e5^2) : 1/(6e5^2) = 2e-13:2.77e-12 Smith et al have better values. They say that this is cooperative, so the consts are now kf/kb =8.3e-4
    3
  • cAMP-bind-site-A
    1
  • cAMP_pathway
    Accession No. : 25
    PKA
    Pathway No. : 135
    75
    (uM^-1 s^-1)
    110
    (s^-1)
    Kd(bf) = 1.4667(uM)-Substrate
    cAMP
    cAMP2.R2C2

    Product
    cAMP3.R2C2
    4
  • cAMP-bind-site-A
    2
  • cAMP_pathway
    Accession No. : 25
    PKA
    Pathway No. : 135
    75
    (uM^-1 s^-1)
    32.5
    (s^-1)
    Kd(bf) = 0.4333(uM)-Substrate
    cAMP
    cAMP3.R2C2

    Product
    cAMP4.R2C2



    Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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