C
Questions? Comments? Please contact Dr. Phillip McClean or Christina Johnson.

OVERVIEW
Flythrough Tour
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MOLECULAR PROCESSES
Transcription
Regulated Transcription
mRNA Processing
mRNA Splicing
Translation
Lac Operon
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CELLULAR PROCESSES
Protein Trafficking
Protein Modification
Protein Recycling
Insulin Signaling
Constitutive Secretion
Regulated Secretion
Mitochondrial Protein Transport
Mitosis
Meiosis
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CELLULAR ENERGY CONVERSION
Atp Synthase (Gradients)
Electron Transport Chain
Photosynthesis (Light Reaction)
Photosystem II
Glycolysis (Overview)
Glycolysis (Reactions)
Citric Acid Cycle (Overview)
Citric Acid Cycle (Reactions)
Energy Consumption
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HOME > PROTEIN RECYCLING > ADVANCED LOOK
Protein Recycling : Advanced Look

Until a mobilization signal is received, glucose transporter 4 (GLUT4) proteins are conserved within muscle and fat cells through a recycling process that cycles them between the plasma membrane and a vesicle storage pool. Clicking on each of the thumbnail images will bring up a larger, labeled version of the described scene.

To see the Flash movie for the following sequence of images, click here.

GLUT4 proteins leave the Golgi apparatus embedded in a transport vesicle.

When glucose levels outside of the cell are low, only a small amount of the GLUT 4 is found in the plasma membrane.

The GLUT4 transporters in the plasma membrane pool are needed to move any available low levels of glucose into the cell.

During such periods of low glucose availability, the majority of the GLUT4 within the cell is found in GLUT4 storage vesicles (GSVs). This is a group of vesicles that cluster together.

When GLUT4 proteins from the plasma membrane bud off and move to the GSV pool, they are replaced by the movement of vesicles from the GSV pool back to the plasma membrane.

Recycling GLUT4 proteins by way of membrane vesicles balances the cell's current need for the GLUT4 protein with the ability to rapidly mobilize available GLUT4 when glucose levels rise.

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