Video Experimental Relacionado
Updated: Jul 21, 2026
09:40
Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum
Published on: September 20, 2011
La supresión por glutamato de la conductancia activada por cGMP en las células bipolares de la retina
Nature
|July 19, 1990
Resumen
El glutamato hiperpolariza las células bipolares despolarizantes de la retina (DBC) mediante la disminución de la conductancia. Esta respuesta implica un proceso mediado por la proteína G, similar a la transducción de luz de los fotorreceptores, mediante el aumento de la hidrólisis cíclica de GMP.
Área de la Ciencia:
- La neurociencia es la neurociencia.
- Fisiología de la retina Fisiología de la retina
- La señalización molecular.
Sus antecedentes:
- Las células bipolares despolarizadas (DBC) en la retina están hiperpolarizadas de manera única por el glutamato.
- El glutamato y el APB disminuyen la conductividad de la membrana DBC, lo que sugiere que está involucrado un segundo sistema mensajero.
Objetivo del estudio:
- Para dilucidar el segundo sistema mensajero que media el efecto hiperpolarizante del glutamato en los DBC.
- Para investigar el mecanismo de activación del receptor de glutamato en los DBC.
Principales métodos:
- Registro de células enteras en rebanadas de retina.
- Aplicación de análogos del glutamato (APB) y aplicación intracelular del GMP/GTP cíclico.
- Uso de GTP-gamma-S, inhibidores de la proteína G y inhibidores de la fosfodiesterasa.
Principales resultados:
- El GMP o GTP cíclico intracelular activó una conductividad de membrana suprimida por APB.
- APB causó supresión irreversible de la conductancia con GTP-gamma-S.
- Los inhibidores de la G-proteína o la fosfodiesterasa redujeron la respuesta de la APB.
Conclusiones:
- El receptor de glutamato DBC cierra los canales iónicos aumentando la hidrólisis cíclica de GMP a través de una vía dependiente de la proteína G.
- Este mecanismo se parece mucho a la fototransducción mediada por la proteína G en los fotorreceptores.
Videos de Conceptos Relacionados
01:15G Protein-coupled Receptors
G Protein-Coupled Receptors or GPCRs are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to sensory stimuli such as light, odors, hormones, cytokines, or neurotransmitters.
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
01:22Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...
01:12GPCR Desensitization
G protein-coupled receptor (GPCR) signaling plays a crucial role in cell functioning. GPCR desensitization is an equally essential process. It allows cells to respond to changing environments and regain sensitivity to new stimuli while preventing unnecessary stimulation when no longer needed. Prolonged exposure to stimuli leads to GPCR desensitization. It involves blocking the receptors from binding and activating additional G proteins. This inhibits activation of downstream effectors, thereby...
01:21G-Protein Gated Ion Channels
GPCRs are primarily responsible for our sense of smell, taste, and vision. The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
Sensory organs,...
Sensory organs,...
01:09GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...
01:30Ligand-Gated Ion Channel Receptor: Gating Mechanism
Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...