Site-site interactions among insulin receptors. Characterization of the negative cooperativity.

摘要: By studying the dissociation of 125I-instulin from its receptors in absence and phe negatively cooperative type for insulin receptors. In present study we extend oy purified mouse rat liver membranes as well human circulating monocytes cultured lymphocytes demonstrated negative cooperativity that was extraordinarily simn more slowly than it does on whole cells. The dissociaty a small percentage receptor sites (1 to 5%), are sufficient accelerate hormone receptor. At these concentrations is entirely monomeric, fact at higher (greater 10(-7) M) where dimers predominate, effect progressively lost. rate 125I-insulin alone (that very low fractional saturation receptors) markedly accelerated by dripping pH 8.0 5.0, whereas high occupancy only slightly fall pH. directly related temperature, but much affected reduction temperature showed sharp transition 21 degrees. Urea 1 M produced marked acceleration dissociation. Divalent cations (calcium magnesium) appear stabilize insulin-receptor interaction, since degrees were required achieve given 125I-insulin. These data make likely exist oligomeric structures or clusters plasma membrane. Insulin switch "slow dissociating" state "fast when their increases; proportion each function monomer physiochemical environment. Other models which could explain apparent besides site-site interactions, i.e. polymerization hormone, steric electrostatic hindrance due ligand-ligand unstirred (Noyes-Whitney) layers considered unlikely case both experimental theoretical grounds.