Members of the VAMP family of synaptic vesicle proteins are components of glucose transporter-containing vesicles from rat adipocytes

• Published in: The Journal of biological chemistry 1992-06, Vol.267 (17), p.11681-11684
• Main Authors: CORLEY CAIN, C, TRIMBLE, W. S, LIENHARD, G. E
• Format: Article
• Language: English
• Subjects: adipocytes; Adipose Tissue - chemistry; Adipose Tissue - cytology; Adipose Tissue - metabolism; Animals; Biological and medical sciences; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell physiology; Electrophoresis, Polyacrylamide Gel; Exocytosis; Fundamental and applied biological sciences. Psychology; glucose transporter; Glucose Transporter Type 4; Insulin - pharmacology; Membrane and intracellular transports; Membrane Proteins - analysis; Membrane Proteins - metabolism; Microsomes - chemistry; Microsomes - metabolism; Molecular and cellular biology; Monosaccharide Transport Proteins - chemistry; Monosaccharide Transport Proteins - metabolism; Muscle Proteins; Nerve Tissue Proteins - analysis; Nerve Tissue Proteins - metabolism; R-SNARE Proteins; Rats; Rats, Inbred Strains; synapses; Synaptic Vesicles - chemistry; Synaptic Vesicles - metabolism; vesicle-associated membrane protein; vesicles
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)49748-2

Existing data support the hypothesis that insulin triggers the exocytosis of small vesicles containing the GluT4 isoform of the glucose transporter. The data also suggest that these vesicles reform through endocytosis of GluT4. These processes resemble those described for synaptic vesicles after depolarization of nerve cells. To determine whether GluT4 vesicles are related to synaptic vesicles, rat adipocyte low density microsomes (LDM), which are rich in GluT4 vesicles, were screened for the synaptic vesicle proteins synaptotagmin, synaptophysin, SV2, p29, rab3, and VAMP (synaptobrevin) by immunoblotting. Two polypeptides that reacted with antibodies against the VAMPs were identified, one with the same apparent size as the two isoforms of VAMP in the brain (18 kDa) and one that was slightly smaller (17 kDa). These members of the VAMP family were highly enriched in GluT4 vesicles isolated by immunoadsorption and translocated from the LDM to the plasma membrane in response to insulin. With the exception of rab3, which was observed in the LDM but was not localized in the GluT4 vesicles, the other synaptic vesicle proteins were not detected. The presence of the VAMPs in both GluT4 and synaptic vesicles suggests that the genesis and/or exocytosis of these two types of vesicles involve shared processes.