INVESTIGADORES
BOUZAT Cecilia Beatriz
artículos
Título:
Number and Locations of Agonist Binding Sites Required to Activate Homomeric Cys-loop Receptors
Autor/es:
RAYES D; DE ROSA MJ; SINE S; BOUZAT C
Revista:
JOURNAL OF NEUROSCIENCE
Editorial:
Society for Neuroscience
Referencias:
Año: 2009 vol. 29 p. 6022 - 6032
ISSN:
0270-6474
Resumen:
Homo-pentameric Cys-loop receptors contain five identical agonist binding sites, each formed at a subunit interface. To determine the number and locations of binding sites required to generate a stable active state, we constructed a receptor subunit with a mutation that disables the agonist binding site and a reporter mutation that alters unitary conductance, and co-expressed mutant and non-mutant subunits. Although receptors with a range of different subunit compositions are produced, patch clamp recordings reveal that the amplitude of each single channel opening event reports the number, and for certain subunit combinations, the locations of subunits with intact binding sites. We find that receptors with three binding sites at non-consecutive subunit interfaces exhibit maximal mean channel open time, receptors with binding sites at three consecutive or two non-consecutive interfaces exhibit intermediate open time, and receptors with binding sites at two consecutive or one interface exhibit brief open time. Macroscopic recordings following rapid application of agonist reveal that channel activation slows and the extent of desensitization decreases as the number of binding sites per receptor decreases. The overall results provide a framework for defining mechanisms of activation and drug modulation for homo-pentameric Cys-loop receptors.