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Updated: May 1, 2026
05:39
Quantitative Measurement of GLUT4 Translocation to the Plasma Membrane by Flow Cytometry
Published on: November 8, 2010
29.1K
The human glucose transporter can insert posttranslationally into microsomes.
Cell
|February 28, 1986
Summary
This study reveals how glucose transporter (GT) proteins insert into membranes. Signal recognition particle (SRP) is crucial for targeting and inserting GT, proposing a new model for protein biosynthesis.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Understanding protein insertion into cellular membranes is fundamental to cell biology.
- The glucose transporter (GT) is a key protein involved in cellular glucose uptake.
- Previous models often assumed a tight ribosome-membrane interaction for protein insertion.
Purpose of the Study:
- To investigate the mechanism of human glucose transporter (GT) insertion into pancreatic microsomes.
- To identify the role of signal sequences and the signal recognition particle (SRP) pathway in GT biosynthesis.
- To propose a novel model for the membrane insertion of GT and related proteins.
Main Methods:
- In vitro synthesis of RNA transcripts for full-length human GT and its fragments (GT-N, GT-C).
- Cell-free synthesis of polypeptides using reticulocyte or wheat germ systems.
- Assessment of membrane insertion using endoglycosidase H, trypsin digestion, and alkaline extraction.
Main Results:
- Both full-length GT and the N-terminal fragment (GT-N) can insert posttranslationally into microsomes.
- GT contains at least two distinct signal sequences.
- Co- and posttranslational insertion of GT-N are dependent on the signal recognition particle (SRP) and SRP receptor.
- SRP is essential for both targeting and initiating the insertion of GT polypeptides.
Conclusions:
- The signal recognition particle (SRP) pathway plays a critical role in the membrane insertion of glucose transporter (GT).
- A model is proposed where GT membrane insertion does not necessitate a tight ribosome-membrane interaction.
- This finding offers new insights into the biosynthesis of transmembrane proteins with complex topologies.
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