Effector Systems of Insulin Signals A Limited Selection

4 Effector Systems of Insulin Signals A Limited Selection 

Glucose transporter Tissue Number of amino acids Chromosomal location Homology to GLUT-4 (%) Appropriate Km for glucose (mM) 

Insulin stimulates glucose transport in typical target tissues such as muscle and adipose tissue. Muscle and fat express predominantly the insulin sensitive GLUT-4 (Fukumoto et al., 1989). Insulin stimulation induces recruitment of GLUT-4 from the intracellular pool to the plasma membrane (Wardzala et al., 1978 Cushman and Wardzala, 1980 Suzuki and Kono, 1980 Kono et al., 1981). 

Recently, increasing evidence for a possible glucose-transport-mediating function for small G-proteins has been produced. Such G-proteins are identified in low-density microsomes (Cormont et al., 1991) where most of the GLUT-4 protein is located before stimulation with insulin. 

A classic cell model widely used to study the signal flow from the receptor to the glucose-transport system is the isolated adipocyte where activation and 

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