Deletion analysis of the human insulin receptor ectodomain reveals independently folded soluble subdomains and insulin binding by a monomeric alpha-subunit.
A series of 13 deletions within the extracellular domain of the human insulin receptor delineates the boundaries of subdomains that fold de novo into stable proteins that are efficiently secreted and retain the epitopes required for interaction with two conformation-specific monoclonal antibodies. While most of these proteins fail to bind insulin, a truncation that includes only the alpha-subunit is secreted as a monomer that binds the hormone with an affinity only slightly less than that of the complete heterotetrameric extracellular domain. These results thus demarcate landmarks within the primary sequence which will now guide further analysis of the structure and function of this complex domain of the receptor.
Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas 75235-9050.
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D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002460:Cell Line; D002850:Chromatography, Gel; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D009154:Mutation; D010957:Plasmids; D011972:Receptor, Insulin / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D014162:Transfection
D007328:Insulin; D046911:Macromolecular Substances; D004247:DNA; D011972:Receptor, Insulin