Inhibition of the binding of SNAP-23 to syntaxin 4 by Munc18c.

SNARE proteins have been implicated in the insulin-induced translocation of vesicles containing the GLUT4 glucose transporter to the plasma membrane of adipocytes. The role of the target SNARE SNAP-25 or its homologs in this process was investigated by screening a mouse adipocyte cDNA library with rat SNAP-25 and human SNAP-23 ...
cDNA probes. Both positive clones isolated encoded a protein with 87% sequence identity to human SNAP-23, and which was therefore designated mouse SNAP-23. Immunoblot and immunofluorescence analyses revealed that SNAP-23 is located predominantly in the plasma membrane of 3T3-L1 adipocytes incubated in the absence or presence of insulin. Of syntaxins 1 to 5, SNAP-23 bound with the highest affinity to syntaxins 1 and 4 in the yeast two-hybrid system. Expression of SNAP-23, syntaxin 4, and the syntaxin-binding protein Munc 18c in COS cells revealed that Munc18c reduced the amount of SNAP-23 bound to syntaxin 4 in a concentration-dependent manner. These results suggest that the binding of SNAP-23 to syntaxin 4 is inhibited by Munc18c in adipocytes.
Mesh Terms:
Adipocytes, Amino Acid Sequence, Animals, Base Sequence, COS Cells, Carrier Proteins, Cloning, Molecular, Glucose Transporter Type 4, Humans, Insulin, Membrane Proteins, Mice, Microscopy, Fluorescence, Molecular Sequence Data, Monosaccharide Transport Proteins, Munc18 Proteins, Muscle Proteins, Nerve Tissue Proteins, Protein Binding, Protein Conformation, Qa-SNARE Proteins, Qb-SNARE Proteins, Qc-SNARE Proteins, Rats, Recombinant Proteins, Sequence Alignment, Sequence Analysis, Transfection, Vesicular Transport Proteins
Biochem. Biophys. Res. Commun.
Date: May. 08, 1997
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