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 l ibrary revealed a peptide, C109 that interacted with the C-terminal cy toplasmic domain of GLUT4 (GLUT4C), cDNA-duced 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) bou nd 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 plas ma membrane GLUT4 level and the 3-O-methyl D glucose flux in host cell s without affecting total cellular GLUT4 content. These findings sugge st that myosin or a myosin-like protein plays a key role in insulin-re gulated movement of GLUT4 to the plasma membrane in rat adipocytes. (C ) 1997 Academic Press.