α‐Helical distorting substitutions disrupt coupling between m3 muscarinic receptor and G proteins

FEBS Letters

Carroll, Reed¹  Clapham, David²  Duerson, Kevin² 

[1] Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, MA 02138, USA;Department of Pharmacology, Mayo Foundation, Rochester, MN 55905, USA

关键词: Xenopus oocyte;    G protein-coupling;    Amphipathic a-helix;    Seven transmembrane-spanning receptors;    Mastoparan;    I Ca-Cl;    calcium-sensitive chloride current;    D1 type;    fast desensitizing current;    f type;    slowly developing oscillatory current;    G proteins;    guanine nucleotide-binding proteins;    mAChR;    muscarinic acetylcholine receptor;    PI;    phosphatidylinositol;    PIP2;    phosphatidylinositol 4;    5-bisphosphate;    Ins(1;    4;    5)P3;    d-myo-inositol 1;    4;    5-trisphosphate;    S.E.M.;    standard error of the mean;    PKC;    protein kinase C;   

DOI  :  10.1016/0014-5793(93)81541-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Acetylcholine stimulation of the m3 or m2 muscarinic receptor expressed in Xenopus laevis oocytes induces either a fast transient or slowly oscillating calcium-sensitive chloride current. The speed of these currents reflects the efficiency of receptor coupling to guanine nucleotide-binding proteins and phosphatidylinositol (PI) turnover. Point mutations of the m3 receptor were made in a region of the third cytoplasmic loop to test whether receptor function relied on an α-helical structure of the G protein-coupling domain. Proline substitution for glutamate at position 257 disrupted the m3 response. Also, single alanine insertions between residues 259 and 260 disrupted the m3 receptor-stimulated response while double alanine insertions at this site had no effect. Based on these results, we suggest that a region of the third cytoplasmic loop of the m3 receptor possesses an amphipathic α-helical conformation.

【 授权许可】

Unknown