Coupling of M3 acetylcholine receptor to Gq16 activates a natriuretic peptide receptor guanylyl cyclase.
Muscarinic activation of tracheal smooth muscle (TSM) involves a M(3)AChR/heterotrimeric-G protein/NPR-GC coupling mechanism. G protein activators Mastoparan (MAS) and Mastoparan-7 stimulated 4- and 10-fold the NPR-GC respectively, being insensitive to PTX and antibodies against Galpha(i/o) subfamily. Muscarinic and MAS stimulation of NPR-GC was blocked by antibodies against C-terminal of Galpha(q16), whose expression was confirmed by RT-PCR. However, synthetic peptides from C-terminal of Galpha(q15/16) stimulated the NPR-GC. Coupling of alpha(q16) to M(3)AChR is supported by MAS decreased [(3)H]QNB binding, being abolished after M(3)AChR-4-DAMP-alkylation. Anti-i(3)M(3)AChR antibodies blocked the muscarinic activation of NPR-GC, and synthetic peptide from i(3)M(3)AChR (M(3)P) was more potent than MAS increasing GTPgamma [(35)S] and decreasing the [(3)H]QNB activities. Coupling between NPR-GC and Galpha(q16) was evaluated by using trypsin-solubilized-fraction from TSM membranes, which displayed a MAS-sensitive-NPR-GC activity, being immunoprecipitated with anti-Galpha(q16), also showing an immunoreactive heterotrimeric-G-beta-subunit. These data support the existence of a novel transducing cascade, involving Galpha(q16)beta gamma coupling M(3)AChR to NPR-GC.
Bruges
Gustavo
G
Sección de Biomembranas, Instituto de Medicina Experimental, Cátedra de Patología General y Fisiopatología, Escuela Luis Razetti, Facultad de Medicina, Universidad Central de Venezuela, Sabana Grande, Caracas, Venezuela.
Borges
Adolfo
A
Sánchez de Villarroel
Sinai
S
Lippo de Bécemberg
Itala
I
Francis de Toba
Gisela
G
Pláceres
Fabiola
F
González de Alfonzo
Ramona
R
Alfonzo
Marcelo J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015153:Blotting, Western; D002417:Cattle; D002846:Chromatography, Affinity; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000302:isolation & purification / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D043585:Receptor, Muscarinic M2 / Q000378:metabolism; D043587:Receptor, Muscarinic M3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism*; D012995:Solubility / Q000187:drug effects; D014357:Trypsin / Q000378:metabolism; D014862:Wasp Venoms / Q000737:chemistry / Q000494:pharmacology
D000906:Antibodies; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D014862:Wasp Venoms; C037500:mastoparan; D006160:Guanosine Triphosphate; D014357:Trypsin; C112631:G protein alpha 16; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor