Structure of insulin/insulin-like growth factor-1 receptors on the insulinoma cell, RIN-m5F.
The subunit structure of receptors for insulin and insulin-like growth factor-1 has been demonstrated on a rat insulinoma cell, RIN-m5F, grown in continuous culture. The specific binding of [125-I]-insulin-like growth factor-1 (2.9 +/- 0.42%; mean +/- SEM) to the RIN-m5F cell was significantly greater than of [125I]-insulin (0.7 +/- 0.2%). Immunoprecipitation of receptors from [125I]-surface labeled cells and analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography revealed reduced subunits of Mr 130,000 and 90,000, identical to those for both insulin and insulin-like growth factor-1 receptors on classic target tissues. An apparent abundance of insulin-like growth factor-1 over insulin receptors could be due to downregulation of the latter by secreted insulin. These findings support a role for insulin and insulin-like growth factor-1 receptors in regulating metabolic or growth functions in the beta cell.
D007516:Adenoma, Islet Cell / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D007328:Insulin / Q000031:analogs & derivatives / Q000378:metabolism; D007340:Insulinoma / Q000378:metabolism*; D046911:Macromolecular Substances; D008970:Molecular Weight; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D051381:Rats; D011972:Receptor, Insulin / Q000302:isolation & purification* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000302:isolation & purification* / Q000378:metabolism; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000378:metabolism
D007328:Insulin; D046911:Macromolecular Substances; D010455:Peptides; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins; C008147:insulin, iodo-; D011972:Receptor, Insulin