title: [Peculiarities of distribution of 125-I-insulin and 125I-insulin-like growth factor-I (IGF-I) at internalization in isolated rat hepatocytes].
abstract: One of determining conditions of formation in vertebrate phylogenesis of hormonal systems of insulin and IGF-I--peptides common by origin, similar by structure and biological action is temperature factor. In differentiation of functional roles of two related hormones and important place id ascribed to mechanism of their intracellular action. Study of formation of the two hormonal systems in vertebrate phylogenesis necessitates knowledge of peculiarities of internalization of two related hormones in mammals. On isolated rat hepatocytes at the identical maximal level of internalization of 125I-insulin and 125I-IGF-I there are revealed marked differences of dynamics of their internalization. Besides, at internalization of 125I-insulin or of 125I-HDP-I, their peculiar distribution was observed in the cell and on the plasma membrane. At 37 degrees C only two thirds of 125I-insulin relative to the bound to receptors on the membrane were immersed into cell, whereas the portion of internalized 125I-IGF-I turned out to be higher than the part located on the membrane. At 12 degrees C the decrease of 125I-insulin inside the cell and its increase on the membrane indicate indicated the interdependent label redistribution under these conditions. The shape of the 125I-iφP-I distribution at low temperature remained unchained. The pattern of established differences of internalization of 125I-insulin and 125I-IGF-I as well as different sensitivity of each of the processes to low temperature indicated that each of the peptides triggered individual mechanism of endocytosis of receptors. The high sensitivity of internalization of 125I-insulin to low temperature and the temperature lability of the process in isolated rat hepatocytes agree with the earlier stated suggestion about the lat formation of the regulatory insulin system in homoiothermal vertebrates.
authors.forename: A P
authors.initials: AP
authors.lastname: Kolychev
authors.forename: E E
authors.initials: EE
authors.lastname: Ternovskaya
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004705:Endocytosis; D022781:Hepatocytes / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar
chemical_list: D007328:Insulin; D007334:Insulin-Like Growth Factor I