Video Experimental Relacionado
Updated: Aug 8, 2026
10:57
Automated System for Single Molecule Fluorescence Measurements of Surface-immobilized Biomolecules
Published on: November 2, 2009
La señalización bidireccional transmembrana por la separación del dominio citoplasmático en las integrinas
Minsoo Kim1, Christopher V Carman, Timothy A Springer
1CBR Institute for Biomedical Research, Department of Pathology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
Science (New York, N.Y.)
|September 23, 2003
Resumen
Las integrinas como LFA-1 sufren cambios conformacionales, separando los dominios citoplasmáticos durante la señalización. Este mecanismo explica cómo las integrinas transmiten señales bidireccionalmente a través de las membranas celulares para procesos biológicos cruciales.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología Molecular Biología Molecular
- Inmunología Inmunología.
Sus antecedentes:
- Las integrinas son receptores críticos de la membrana plasmática involucrados en el desarrollo, la inmunidad, la cicatrización de heridas y la metástasis.
- Los mecanismos fundamentales de señalización de las integrinas han permanecido en gran parte desconocidos.
- La integrina LFA-1 (alphaLbeta2) juega un papel clave en la adhesión y el tráfico de células inmunes.
Objetivo del estudio:
- Para investigar los cambios conformacionales citoplasmáticos en la integrina LFA-1 dentro de las células vivas.
- Para dilucidar el mecanismo molecular de la señalización bidireccional de integrinas (de adentro hacia afuera y de afuera hacia adentro).
- Para entender cómo las integrinas transmiten señales a través de la membrana plasmática.
Principales métodos:
- Utilizó la transferencia de energía de resonancia de fluorescencia (FRET) para medir la proximidad espacial.
- Proteínas de fusión de proteína fluorescente ciano (CFP) y proteína fluorescente amarilla (YFP) diseñadas para los dominios citoplasmáticos alphaL y beta2.
- Cambios conformacionales observados en los estados de reposo y activado de LFA-1 en células vivas.
Principales resultados:
- En estado de reposo, los dominios citoplasmáticos alphaL y beta2 de LFA-1 estaban muy cerca.
- Se produjo una separación espacial significativa de los dominios citoplasmáticos tras la activación de adherencia interna hacia afuera (aumento de la adherencia).
- La unión de ligandos (señalización exterior-interior) también indujo una separación espacial sustancial de estos dominios.
Conclusiones:
- La señalización bidireccional de integrinas está mediada por el desagrupamiento y la separación de los dominios citoplasmáticos alfa y beta.
- Este cambio conformacional representa un nuevo mecanismo para la transmisión de señales transmembrana.
- Comprender la dinámica conformacional de las integrinas proporciona información sobre las respuestas inmunes y los procesos de enfermedad.
Videos de Conceptos Relacionados
01:26Insertion of Single-pass Transmembrane Proteins in the RER
Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
01:29Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
00:59Mechanisms of Membrane Domain Formation
Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
01:10Integrins
Animal and protozoan cells do not have cell walls to help maintain shape and provide structural stability. Instead, these eukaryotic cells secrete a sticky mass of carbohydrates and proteins into the spaces between adjacent cells. This network of proteins and molecules is called an extracellular matrix or ECM.
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...
01:15Activation of Integrins
Integrins bind ligands and transmit information from outside the cell to inside or vice-versa through an "outside-in signaling" or "inside-out signaling."
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
01:17Intracellular Signaling Affects Focal Adhesions
Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Some...