A myosin-derived peptide C109 binds to GLUT4-vesicles and inhibits the insulin-induced glucose transport stimulation and GLUT4 recruitment in rat adipocytes.

The yeast-based two-hybrid screening of a human cardiac myocyte cDNA library revealed a peptide, C109 that interacted with the C-terminal cytoplasmic domain of GLUT4 (GLUT4C). cDNA-deduced amino acid sequence of C109 was identical to the human cardiac muscle myosin heavy chain beta isoform sequence 1469-1909. GST-fusion protein of C109 (GST-C109) bound synthetic GLUT4C-peptide in vitro, but not GLUT1C-peptide. GST-C109 avidly bound to the GLUT4-vesicles isolated from basal rat adipocytes but not those isolated from insulin treated adipocytes. Furthermore, the incorporation of C109 into rat adipocytes greatly reduced the plasma membrane GLUT4 level and the 3-O-methyl D glucose flux in host cells without affecting total cellular GLUT4 content. These findings suggest that myosin or a myosin-like protein plays a key role in insulin-regulated movement of GLUT4 to the plasma membrane in rat adipocytes.