Negative and positive site-site interactions, and their modulation by pH, insulin analogs, and monoclonal antibodies, are preserved in the purified insulin receptor.

AUTOR(ES)

Wang, C C

RESUMO

The kinetic properties of the insulin receptor were studied in solution after its purification to homogeneity. Dissociation of 125I-labeled insulin at a 1:50 dilution was not first order; unlabeled insulin at physiological concentrations accelerated the dissociation rate with a maximal effect at approximately 17 nM. At higher concentrations, the unlabeled insulin slowed the dissociation rate. Maximal acceleration was seen at pH 8.0. The ability to accelerate the dissociation rate was diminished with [LeuB24]insulin and suppressed with desoctapeptide, [LeuB25], [LeuB24,B25], desalanine-desasparagine, and desheptapeptide insulins, all of which slowed the dissociation at high concentrations. Monoclonal antibodies to the insulin receptor alpha subunit (MA-5, MA-10, MA-20, and MA-51) all competed for insulin binding to the purified receptor. MA-10 and MA-51 accelerated the dissociation of 125I-labeled insulin, while MA-5 and MA-20 slowed the off rate. Thus, all the aspects of both negatively and positively cooperative site-site interactions previously described in whole cells are present in solubilized purified receptors, demonstrating that these interactions represent intrinsic properties of the receptor molecule, most likely as a result of ligand-induced conformational changes.

Documentos Relacionados

• Negative pH, efflorescent mineralogy, and consequences for environmental restoration at the Iron Mountain Superfund site, California
• Growth-stimulatory monoclonal antibodies against human insulin-like growth factor I receptor.
• Monoclonal antibodies to human estrogen receptor.
• Escherichia coli intracellular pH, membrane potential, and cell growth.
• Proteinase sensitivity of bacteriophage lambda tail proteins gpJ and pH in complexes with the lambda receptor.