ABSTRACT

In insulin-sensitive tissues, insulin facilitates glucose entry into cells by increasing the number of specific glucose transporters (GLUT 4s) in the cell membrane. These glycoprotein transporters are recruited from the Golgi fraction to the plasma membrane, a process which is both temperature and energy dependent. Exercise, which is associated with low insulin levels, encourages GLUT 4 recruitment into plasma membranes of exercising muscle cells without the assistance of insulin. Seven different GLUTs have been identified, but only GLUT 4 is insulinsensitive. The 6 non-insulin-sensitive GLUTs appear to remain in their cell membranes.