PMID: 6986378Feb 25, 1980Paper

The subunit structure of the high affinity insulin receptor. Evidence for a disulfide-linked receptor complex in fat cell and liver plasma membranes.

The Journal of Biological Chemistry
P F Pilch, M P Czech

Abstract

125I-Insulin equilibrated with high affinity fat cell and liver plasma membrane receptors was cross-linked to the membrane by addition of disuccinimidyl suberate. Autoradiographic analysis of the 125I-insulin-linked membranes subsequent to dodecyl sulfate electrophoresis in the absence of reductant revealed the presence of one labeled species which migrated with an apparent molecular weight of 300,000. Electrophoresis of these membranes in the presence of dithiothreitol resulted in the appearance of one major labeled band of about Mr = 125,000 concomitant with the loss of label in the Mr = 300,000 region. Another radioactive species which migrated in the Mr = 225,000 region on the reduced gels contained a much smaller amount of label. The degree to which the Mr = 125,000 membrane component was cross-linked to 125I-insulin in these experiments paralleled the extent of occupancy of high affinity membrane receptors by the 125I-insulin. 125I-Insulin-linked plasma membranes derived from adipocytes alkylated with N-ethylmaleimide prior to homogenization to prevent spontaneous sulfhydryl oxidation also exhibited the Mr = 300,000 and 125,000 labeled bands upon electrophoresis in the absence and presence of reductant, respectively. The...Continue Reading

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