Putting the brakes on a myosin motor.

ABSTRACT

Insulin-stimulated trafficking of GLUT4 requires the myosin motor Myo1C and signaling adaptor 14-3-3ß. Originally, it was thought that 14-3-3ß promotes GLUT4 transport by binding the Myo1C lever arm and activating the Myo1C motor. New work by Ji and Ostap using in vitro assays reveals that 14-3-3ß binding actually inhibits Myo1C motility, prompting reconsideration of the functional relationship between 14-3-3ß and Myo1C and the regulatory potential of atypical light chains.