Protein Internalization
Protein Internalization - Related Videos
05:16
Assessing the Internalization of Target Surface Proteins Using a Biotin Derivative
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2025
This video demonstrates a method to assess target protein internalization in the mouse cortical astrocytes using biotinylation, followed by cell lysis, streptavidin-based protein extraction, denaturation, and Western blot analysis to confirm successful internalization.
10:24
Detection of Ligand-activated G Protein-coupled Receptor Internalization by Confocal Microscopy
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Cited by 2 •
2017
This protocol describes confocal microscopy detection of G protein-coupled receptor (GPCR) internalization in mammalian cells. It includes the basic cell culture, transfection, and confocal microscopy procedure and provides an efficient and easily interpretable method to detect the subcellular localization and internalization of fusion-expressed GPCR.
11:56
Differential Labeling of Cell-surface and Internalized Proteins after Antibody Feeding of Live Cultured Neurons
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Cited by 24 •
2014
We describe a method to label protein on the surface of living neurons using a specific polyclonal antibody to extracellular epitopes. Protein bound by the antibody on the cell surface and subsequently internalized via endocytosis can be distinguished from protein remaining on, or trafficked to, the surface during the incubation.
09:18
Internal Standards
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2023
Source: Laboratory of Dr. B. Jill Venton - University of Virginia The goal of many chemical analyses is a quantitative analysis, where the amount of a substance in a sample is determined. In order to accurately calculate the concentration of an unknown from a sample, careful sample preparation is key. Every time a sample is handled or transferred, some of the sample can be lost. There are strategies however, for minimizing sample loss. There are also strategies for coping with sample loss and...
02:00
Internal Energy
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2020
The total of all possible kinds of energy present in a substance is called the internal energy (U), sometimes symbolized as E. Suppose a system with initial internal energy, Uinitial, undergoes a change in energy (transfer of work or heat), and the final internal energy of the system is Ufinal. Change in internal energy equals the difference between Ufinal and Uinitial. Although the values for Ufinal and Uinitial cannot be determined for a system, the first law of thermodynamics only...
FAQs
Receptor binding can provide the trigger that draws a protein toward a cell surface entry site. The interaction is followed by plasma-membrane invagination, formation of an internal vesicle, and movement into endosomal compartments. This sequence links recognition outside the cell with later outcomes such as signaling changes, nutrient acquisition, degradation, recycling, or delivery toward the cytosol.
Endosomal compartments act as intracellular routing stations after vesicle formation. They help determine whether an internalized protein proceeds toward degradation, returns through recycling pathways, or reaches the cytosol. Identifying the protein’s route is important because cellular uptake alone does not reveal whether the molecule remains available for signaling, is broken down, or supports molecular delivery.
A protein can associate with the cell surface without crossing the plasma membrane, so surface binding alone does not demonstrate internalization. Separating these outcomes allows researchers to interpret uptake measurements accurately and avoid attributing intracellular effects to proteins that remain outside the cell. This distinction is particularly important when evaluating receptor function, trafficking, or delivery performance.
Protein internalization may begin through membrane interactions as well as receptor binding. In either case, the interaction can promote membrane invagination and vesicle formation, but the resulting intracellular routing determines the biological consequence. Considering both entry triggers helps investigators examine how proteins influence cell behavior without assuming that every uptake event depends on a defined receptor.
An analysis can follow the protein from its initial association with the cell surface through vesicle formation and passage into endosomal compartments. Researchers then determine whether it is degraded, recycled, or routed to the cytosol, while separately assessing surface binding. This workflow connects the observed uptake event with its actual intracellular destination and biological outcome.
Studying this process is especially useful when investigators need to understand receptor function, intracellular trafficking, or how proteins alter cell behavior. It also supports research on nutrient acquisition and molecular delivery. By examining where an internalized protein goes rather than only whether it enters, researchers can connect cellular uptake with specific functional or delivery-related outcomes.
Protein internalization provides a framework for evaluating whether an externally supplied protein reaches an intracellular destination. Tracking its movement through endosomal compartments can show whether it is degraded, recycled, or routed to the cytosol. These outcomes are relevant to therapeutic development and protein-based delivery systems because successful entry alone may not produce the intended intracellular effect.