Video Experimental Relacionado

Updated: May 5, 2026

Transmembrane Domain Oligomerization Propensity determined by ToxR Assay

Transmembrane Domain Oligomerization Propensity determined by ToxR Assay

Published on: May 26, 2011

Los péptidos transmembranares extraños que reemplazan la secuencia de señal interna del receptor de transferrina

M Zerial, D Huylebroeck, H Garoff

|January 16, 1987

Resumen

El segmento transmembrana del receptor de transferrina (TR) es crucial para su función. Su naturaleza hidrofóbica, no aminoácidos específicos, impulsa la translocación de la cadena y el anclaje de la membrana para la inserción de TR en la membrana ER.

Área de la Ciencia:

Biología celular Biología celular.
Biología Molecular Biología Molecular
Biología de las proteínas de membrana Biología de las proteínas de membrana Biología de las proteínas de membrana

Sus antecedentes:

El receptor humano de transferrina (TR) es una proteína transmembrana esencial para la absorción de hierro.
Cada subunidad TR se inserta en la membrana del retículo endoplasmático (ER) con su N-terminal en el citoplasma.
El segmento transmembranar de TR juega un doble papel: señalización para la translocación de proteínas y anclaje de la proteína dentro de la membrana.

Objetivo del estudio:

Investigar los requisitos estructurales específicos del segmento transmembrana TR para su doble función en la translocación de proteínas y el anclaje de la membrana.
Para determinar si la secuencia de aminoácidos o la naturaleza hidrofóbica del segmento transmembrana es crítica para su actividad.

Principales métodos:

Mutagenesis del segmento transmembrana TR.
Sustitución del péptido transmembrana TR nativo por segmentos de otras proteínas o un péptido artificial.
Pruebas de translocación in vitro para evaluar la función de las moléculas TR mutantes.

Principales resultados:

Las moléculas TR mutantes con segmentos transmembranales sustituidos (incluido un péptido sin carga artificial) se translocaron de manera eficiente in vitro.
La sustitución del péptido transmembrana TR por un péptido hidrófilo abolió la actividad de translocación detectable.
Estos hallazgos indican que el carácter hidrofóbico es esencial para la función del segmento transmembrana.

Conclusiones:

La naturaleza hidrofóbica del segmento transmembrana del receptor de transferrina es fundamental para su papel en la translocación de la cadena y la unión a la membrana.
La secuencia específica de aminoácidos de este segmento es menos importante que su hidrofobia general para estas funciones.
Este estudio aclara las características clave que rigen la inserción y la función de las proteínas transmembrana.

Más Videos Relacionados

Measuring Peptide Translocation into Large Unilamellar Vesicles

Measuring Peptide Translocation into Large Unilamellar Vesicles

Published on: January 27, 2012

Fluorescent Leakage Assay to Investigate Membrane Destabilization by Cell-Penetrating Peptide

Fluorescent Leakage Assay to Investigate Membrane Destabilization by Cell-Penetrating Peptide

Published on: December 19, 2020

Videos de Conceptos Relacionados

The Early Endosome: Endocytosis of Transferrin

The Early Endosome: Endocytosis of Transferrin

Essential proteins such as insulin or low-density lipoprotein (LDL) and micronutrients such as iron enter a eukaryotic cell through receptor-mediated endocytosis. Subsequently, the early endosomes fuse with the vesicles containing such receptor-ligand complexes and play a vital role in sorting the incoming ligands and receptors. While the ligands are either degraded inside the vesicle or released into the cytosol, their receptors are returned to the plasma membrane for further rounds of...

Translocation of Proteins into the Mitochondria

Translocation of Proteins into the Mitochondria

Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...

Protein Transport into the Inner Mitochondrial Membrane

Protein Transport into the Inner Mitochondrial Membrane

Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...

Insertion of Single-pass Transmembrane Proteins in the RER

Insertion 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...

Insertion of Multi-pass Transmembrane Proteins in the RER

Insertion 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...

Post-translational Translocation of Proteins to the RER

Post-translational Translocation of Proteins to the RER

A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...