Insulin, rapidly and independently of new protein synthesis, stimulates glucose transport in sensitive target tissues. A cDNA has been cloned from a skeletal muscle library that encodes a novel glucose transporter protein exhibiting the following properties of an insulin-regulated hexose carrier protein: it is expressed exclusively in adipose tissue, skeletal muscle and heart, the principal organs with insulin-responsive glucose transport; RNA transcribed from the muscle cDNA, when expressed in Xenopus oocytes, encodes a protein capable of cytochalasin B inhibitable 2-deoxyglucose transport; and treatment of isolated rat adipocytes with insulin effects a redistribution of "muscle" transports from low density microsomes to the plasma membrane to an extent comparable to the activation of glucose transport.