Video Experimental Relacionado
Updated: May 9, 2026
09:00
Cargo Loading onto Kinesin Powered Molecular Shuttles
Published on: November 3, 2010
Bases estructurales para la regulación de la carga del conjunto de capas COPII
Scott M Stagg1, Paul LaPointe, Abbas Razvi
1National Resource for Automated Molecular Microscopy, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Cell
|August 12, 2008
Resumen
Los investigadores visualizaron la estructura de la capa COPII, revelando cómo los adaptadores de carga y las proteínas de celosía se ensamblan para exportar proteínas desde el retículo endoplasmático (ER). Esta estructura explica cómo la capa se expande para acomodar una carga voluminosa, crucial para la función celular y la comprensión de la enfermedad.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- El mecanismo COPII (Complejo de Proteínas de la Capa II) media la formación de vesículas de transporte desde el retículo endoplasmático (ER).
- Comprender la base estructural del ensamblaje de la capa COPII es crucial para descifrar las vías de exportación de proteínas.
- El transporte COPII disfuncional está implicado en varias enfermedades hereditarias.
Objetivo del estudio:
- Para determinar la estructura de alta resolución de la capa COPII icosidodecaédrica.
- Para aclarar el mecanismo de ensamblaje de capa COPII y su interacción con la carga.
- Proporcionar información sobre cómo la estructura de la capa COPII facilita la exportación de carga y el brote de la membrana.
Principales métodos:
- Se utilizó la microscopía cryoelectrónica (cryo-EM) para resolver la estructura de la capa COPII ensamblada.
- Adaptadores de carga purificados (Sec23-24) y complejos formadores de celosía (Sec13-31) fueron coensamblados.
- Las estructuras cristalinas conocidas de las proteínas COPII se ajustaron al mapa de densidad cryo-EM.
Principales resultados:
- La estructura revela una capa adaptadora tetramérica Sec23-24 colocada debajo de la red Sec13-31.
- Una región de bisagra flexible, que involucra los dominios WD40 de Sec13 y Sec31, permite la expansión geométrica de la jaula.
- La estructura de la capa acomoda cargas voluminosas, como el procollageno y los quilomicrones, destacando la sensibilidad del adaptador en enfermedades.
Conclusiones:
- La estructura de capa COPII proporciona un modelo mecanicista para el ensamblaje impulsado por carga y la curvatura de la membrana durante el brote de ER.
- El mecanismo de bisagra flexible permite el alojamiento de diversas y voluminosas moléculas de carga.
- Esta comprensión estructural es vital para investigar el transporte mediado por la COPII y las patologías asociadas.
Más Videos Relacionados
11:09Characterizing the Composition of Molecular Motors on Moving Axonal Cargo Using "Cargo Mapping" Analysis
Published on: October 30, 2014
05:47Simulation of a Scaled Assembly Process with Collaboration of a Robotic Arm and Monitoring through a Vision System for Quality Control
Published on: August 29, 2025
Videos de Conceptos Relacionados
02:22Regulated mRNA Transport
In eukaryotes, transcription and translation are compartmentalized; an mRNA is first synthesized in the nucleus and then selectively transported to the cytoplasm for protein synthesis. Before transport, a pre-mRNA undergoes several steps of post-transcriptional modifications including splicing, 5' capping, and the addition of a poly-adenine tail. Various proteins bind to the pre-mRNA during these modifications. The mRNA transport takes place with the help of multiple proteins playing specific...
01:45Regulation of Nuclear Protein Sorting
Nuclear protein sorting regulates nucleus composition and gene expression, crucial for determining the fate of a eukaryotic cell. Hence, the entry and exit of molecules across the nuclear envelope is a tightly controlled process. Nuclear protein sorting can be inhibited by one of the following ways: 1) masking cargo signal sequences, 2) modifying the nuclear receptor's affinity for cargo, 3) controlling the nuclear pore size, 4) retaining the cargo during its transit to the cytosol or the...
00:59COP Coated Vesicles
Membrane-enclosed structures called vesicles transport proteins and lipids across the cell. The vesicles derive their cargo from the plasma membrane, Golgi, ER, or endosome. Coated vesicles are spherical, protein-coated carriers with a 50–100 nm diameter that mediate bidirectional transport between the ER and the Golgi. The distribution of proteins between the ER and Golgi complex is dynamic and is maintained by different coated vesicles. Their formation is driven by the assembly of different...
01:32Pinching-off of Coated Vesicles
Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
01:33Coat Assembly and GTPases
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
01:26Transport Across the Golgi
While it is unclear how molecules move between adjacent Golgi cisternae, it is apparent that the molecules move from cis- cisterna, the entry face, to the trans- cisterna, the exit face. Experiments initially suggested vesicles that bud from one cisterna and fuse with the next cisterna to transport proteins between the cisternae. This vesicular transport model describes the Golgi apparatus as a relatively static structure with a unique enzyme composition in each cisterna. Molecules are...