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Insulin-stimulated GLUT4 glucose transporter recycling. A problem in membrane protein subcellular trafficking through multiple pools
The subcellular trafficking of GLUT4 in isolated rat adipose cells and 3T3-L1 adipocytes exhibits many of the properties observed in regulated secretory processes and neurosecretion. GLUT4 is sorted and sequestered from endosomes into a specialized secretory compartment in the basal state and the in...
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Published in: | The Journal of biological chemistry 1994-07, Vol.269 (26), p.17516-17524 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The subcellular trafficking of GLUT4 in isolated rat adipose cells and 3T3-L1 adipocytes exhibits many of the properties observed
in regulated secretory processes and neurosecretion. GLUT4 is sorted and sequestered from endosomes into a specialized secretory
compartment in the basal state and the initial stimulation of its exocytosis by insulin is more rapid than its recycling through
the endosomes and secretory compartment during the steady-state response to insulin. We present a mathematical analysis which
shows that this behavior is inconsistent with a simple 2-pool model with one plasma membrane and one intracellular compartment,
but that a 3-pool model, with two intracellular compartments, can simulate these properties. We extend this model to include
the presence of occluded pools in the plasma membrane. Our analysis compares the behavior expected when these occluded pools
are precursors in stimulation and/or clathrin-associated-like intermediates in endocytosis. The presence of a precursor occluded
pool can account for a lag between the appearance of GLUT4 in the membrane and before the full stimulation of glucose transport
activity. The analysis also shows that since the pool size of the occluded GLUT4 is relatively small, the formation of endocytic
occluded intermediates such as GLUT4 in clathrin-coated pits is likely to be slow compared with the rate of endocytosis of
the coated vesicles. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)32471-7 |