The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Insulin action rapidly modulates the apparent affinity of the insulin-like growth factor II receptor.

Incubation of intact rat adipocytes with physiological concentrations of insulin stimulates binding of insulin-like growth factor II (IGF-II) to its receptor by 3- to 10-fold. The effect is temperature- and dose-dependent, with 0.1 nM insulin giving half-maximal stimulation. Scatchard analysis of IGF-II binding to intact adipocytes indicates that this effect is due to an apparent increase in receptor affinity, from Kd = 63 nM in the absence of insulin to Kd = 5.8 nM in the presence of 10 nM insulin, with no apparent change in the number of cell surface binding sites (220,000/cell). Scatchard analysis of 125I-IGF-II binding to isolated membrane fractions demonstrated that all IGF-II receptors in plasma membranes and low density microsomes from control cells are converted during homogenization to the high affinity form (Kd = 2 to 6 nM) seen in insulin-treated intact adipocytes. No significant difference in affinity was observed between plasma membranes from control or insulin-treated adipocytes or between low density microsomes from control or insulin-treated cells. However, in apparent contrast to the results obtained in intact adipocytes, the number of binding sites is increased in the plasma membrane fraction from insulin-treated cells by an average of 60%, while the number of receptors is decreased by 40% in low density microsomes from insulin-treated cells compared to control cells. These results were confirmed by direct visualization of the Mr = 270,000 IGF-II receptor band on dodecyl sulfate gels following affinity labeling with 125I-IGF-II and the cross-linker disuccinimidyl suberate. Scatchard analysis of the total cellular membranes showed no difference in the total number of binding sites between control and insulin-treated cells. These results demonstrate that insulin has two effects on the IGF-II receptor in adipocytes. 1) It rapidly increases the apparent affinity of the receptor in the intact cell without changing the apparent number of receptors on the cell surface; and 2) it induces a redistribution of the high affinity IGF-II receptor between plasma membranes and low density microsomes upon homogenization of cells and preparation of membranes. The latter effect closely parallels the insulin-induced membrane redistribution of the glucose transporter that occurs in the rat adipocyte by an unknown mechanism.[1]


  1. Insulin action rapidly modulates the apparent affinity of the insulin-like growth factor II receptor. Oppenheimer, C.L., Pessin, J.E., Massague, J., Gitomer, W., Czech, M.P. J. Biol. Chem. (1983) [Pubmed]
WikiGenes - Universities