Insulin stimulation of 3T3-L1 adipocytes causes rapid translocation of actin and the GLUT4
glucose transporter to the plasma membrane. Both processes depend on the activity of
phosphatidylinositol 3-kinase. Using single cell microinjection, we have transiently
expressed a constitutively activated mutant of phosphatidylinositol 3-kinase, p110*, in 3T3-
L1 adipocytes. Fluorescent detection of GLUT4 protein and actin within these cells
demonstrates that expression of p110* is sufficient to cause translocation of GLUT4 to the …