Agonist‐stimulated high‐affinity GTPase in Dictyostelium membranes

FEBS Letters

Van Haastert, Peter J.M.²  Jakobs, Karl H.¹  Snaar-Jagalska, B.Ewa² 

[1] Pharmakologisches Institut der Universität Heidelberg, Im Neuenheimer Feld 366, D-6900 Heidelberg, FRG;Cell Biology and Genetics Unit, Zoological Laboratory, PO Box 9516, 2300 RA Leiden, The Netherlands

关键词: Enzyme activity;    GTPase;    GTP hydrolysis;    cyclic AMP;    Pertussis toxin;    G-protein;    ATPγS;    adenosine 5′-O-(3-thiotriphosphate);    AppNHp;    adenylyl-imidodiphosphate;    cAMP;    adenosine 3′;    5′-monophosphate;    (Sp)-cAMPS;    adenosine 3′;    5′-monophosphorothioate;    Sp-stereoisomer;    2′-dcAMP;    2′-deoxyadenosine 3′;    5′-monophosphate;    8-Br-cAMP;    8-bromo-adenosine 3′;    5′-monophosphate;    cGMP;    guanosine 3′;    5′-monophosphate;    5′-AMP;    adenosine 5′-monophosphate;    DTT;    dithiothreitol;   

DOI  :  10.1016/0014-5793(88)80302-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

GTP hydrolysis in Dictyostelium discoideum membranes is caused by a low (K _m> 1 mM) and a high affinity (K _m 6.5 μM) GTPase. cAMP enhances GTP hydrolysis apparently by increasing the affinity of the high affinity GTPase (stimulated K _m 4.5 μM); the low affinity GTPase was not affected by cAMP. Stimulation of GTP hydrolysis by cAMP was maximal at early time points and declined thereafter. A half-maximal stimulation of GTPase occurred at 3 μM cAMP and the specificity of cAMP derivatives for stimulation of GTPase activity showed a close correlation with the specificity for binding to the cell surface cAMP receptor. Treatment of D. discoideum cells with pertussis toxin decreased the cAMP-induced stimulation of GTPase from 42 ± 6% in control cells to 17 ± 9% in pertussis toxin-treated cells. These results suggest that the interaction of cAMP with its surface receptor leads to stimulation of high affinity GTPase in D. discoideum membranes. At least one of those enzymes may represent a guanine nucleotide-binding protein sensitive to pertussis toxin.

【 授权许可】

Unknown