Arachidonate and related unsaturated fatty acids selectively inactivate the guanine nucleotide-binding regulatory protein, G(z)

被引:47
作者
Glick, J [1 ]
Santoyo, G [1 ]
Casey, PJ [1 ]
机构
[1] DUKE UNIV, MED CTR, DEPT BIOCHEM, DURHAM, NC 27710 USA
关键词
D O I
10.1074/jbc.271.6.2949
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
G(z) is a member of the family of trimeric guanine nucleotide-binding regulatory proteins (G proteins) which plays a crucial role in signaling across cell membranes. The expression of G(z) is predominately confined to neuronal cells and platelets, suggesting an involvement in a neuroendocrine process. Although the signaling pathway in which G(z) participates is not yet known, it has been linked to inhibition of adenylyl cyclase. We have found that arachidonate and related unsaturated fatty acids suppress guanine nucleotide binding to the alpha subunit of G(z). This inhibition of nucleotide binding by cis-unsaturated fatty acids is specific for G(z alpha); other G protein alpha subunits are relatively insensitive to these lipids. The IC50 for inhibition by the lipids closely corresponds to their critical micellar concentrations, suggesting that the interaction of the lipid micelle with G(z alpha) is the primary event leading to inhibition. The presence of the acidic group of the fatty acid is critical for inhibition, as no effect is observed with the corresponding fatty alcohol. While arachidonic acid produces near-complete inhibition of both GDP and guanosine 5'-(3-O-thio)triphosphate binding by G(z alpha), release of GDP from the protein was unaffected. Furthermore, the rate of inactivation of G(z alpha) by arachidonate is essentially identical to the rate of GDP release from the protein, indicating that GDP release is required for inactivation. These observations indicate that the mechanism of inactivation of G(z alpha) by unsaturated fatty acids is through an interaction of an acidic lipid micelle with the nucleotide-free form of the protein. Although the physiologic significance of this finding is unclear, similar effects of unsaturated fatty acids on other proteins involved in cell signaling indicate potential roles for these lipids in signal modulation. Additionally, the ability of arachidonate to inactivate this adenylyl cyclase-inhibitory G protein provides a molecular mechanism for previous findings that treatment of platelets with arachidonate results in elevated cAMP levels.
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页码:2949 / 2954
页数:6
相关论文
共 35 条
[1]  
CASEY PJ, 1990, J BIOL CHEM, V265, P2383
[2]   FLUORIMETRIC DETERMINATION OF CRITICAL MICELLE CONCENTRATION AVOIDING INTERFERENCE FROM DETERGENT CHARGE [J].
CHATTOPADHYAY, A ;
LONDON, E .
ANALYTICAL BIOCHEMISTRY, 1984, 139 (02) :408-412
[3]  
CHUANG TH, 1993, J BIOL CHEM, V268, P26206
[4]   NEW ROLES FOR G-PROTEIN BETA-GAMMA-DIMERS IN TRANSMEMBRANE SIGNALING [J].
CLAPHAM, DE ;
NEER, EJ .
NATURE, 1993, 365 (6445) :403-406
[5]  
FERGUSON KM, 1986, J BIOL CHEM, V261, P7393
[6]   PHOSPHORYLATION OF C-Z-ALPHA BY PROTEIN-KINASE-C BLOCKS INTERACTION WITH THE BETA-GAMMA COMPLEX [J].
FIELDS, TA ;
CASEY, PJ .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1995, 270 (39) :23119-23125
[7]   IDENTIFICATION OF A GTP-BINDING PROTEIN ALPHA-SUBUNIT THAT LACKS AN APPARENT ADP-RIBOSYLATION SITE FOR PERTUSSIS TOXIN [J].
FONG, HKW ;
YOSHIMOTO, KK ;
EVERSOLECIRE, P ;
SIMON, MI .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1988, 85 (09) :3066-3070
[8]   ARACHIDONIC-ACID RELEASE AND CATECHOLAMINE SECRETION FROM DIGITONIN-TREATED CHROMAFFIN CELLS - EFFECTS OF MICROMOLAR CALCIUM, PHORBOL ESTER, AND PROTEIN ALKYLATING-AGENTS [J].
FRYE, RA ;
HOLZ, RW .
JOURNAL OF NEUROCHEMISTRY, 1985, 44 (01) :265-273
[9]   THE RELATIONSHIP BETWEEN ARACHIDONIC-ACID RELEASE AND CATECHOLAMINE SECRETION FROM CULTURED BOVINE ADRENAL CHROMAFFIN CELLS [J].
FRYE, RA ;
HOLZ, RW .
JOURNAL OF NEUROCHEMISTRY, 1984, 43 (01) :146-150
[10]   G-PROTEINS - TRANSDUCERS OF RECEPTOR-GENERATED SIGNALS [J].
GILMAN, AG .
ANNUAL REVIEW OF BIOCHEMISTRY, 1987, 56 :615-649