Binding and molecular weight properties of the insulin receptor from omental and subcutaneous adipocytes in human obesity.
Binding and molecular weight properties of the insulin receptor from omental and subcutaneous adipocytes in human obesity.
复制标题
人类肥胖中网膜和皮下脂肪细胞胰岛素受体的结合和分子量特性。
作者：
Livingston,JN;Lerea,KM;Bolinder,J;Kager,L;Backman,L;Arner,P
在从肥胖和正常体重受试者制备的网膜和皮下脂肪细胞中研究了胰岛素结合特性以及胰岛素受体及其胰岛素结合亚基的分子量。当结合活性以每单位细胞表面积表示时，肥胖中此类脂肪细胞的胰岛素结合减少。然而，当以每个细胞为基础计算结合时，与瘦对照没有明显差异，这表明来自肥胖受试者的细胞的总受体含量没有改变。此外，先前报道的瘦个体的网膜细胞和皮下细胞之间受体结合亲和力的正常差异不受肥胖状况的影响。对由网膜和皮下脂肪片制备的脂肪细胞膜中非还原胰岛素受体分子量的研究表明，主要受体种类为 390-425K Mr。相比之下，通过胶原酶处理脂肪分离的脂肪细胞具有异质非还原受体种类 Mr355K、285K 以及少量的 427K 和 182K。尽管根据脂肪细胞受体制备（例如分离的脂肪细胞或脂肪细胞膜），不同的非还原受体种类是明显的，但当进行适当的比较时，肥胖和瘦对照之间或皮下和网膜受体之间没有发现差异。巯基还原后，所有受体制剂均具有 125K Mr 的主要结合亚基。 总之，肥胖症的特征是脂肪细胞表面上的胰岛素受体稀释，而受体的总细胞含量没有变化。大网膜和皮下脂肪细胞之间胰岛素结合亲和力的差异不能用受体分子量的变化来解释。
The insulin binding properties and the molecular weights of the insulin receptor and its insulin binding subunit were studied in omental and subcutaneous adipocytes prepared from obese- and normal-weight subjects. Insulin binding by such adipocytes was decreased in obesity when the binding activity was expressed per unit of cell surface area. No significant difference from the lean controls was evident, however, when binding was calculated on a per cell basis, indicating that the total receptor content of the cells from the obese subjects was not altered. In addition, the normal difference in the receptor binding affinities previously reported between omental and subcutaneous cells from lean individuals was unaffected by the obese condition. Studies of the molecular weight of the non-reduced insulin receptor in fat cell membranes prepared from pieces of omental and subcutaneous fat demonstrated a major receptor species of 390–425K Mr. In contrast, adipocytes isolated by collagenase treatment of the fat had heterogenous non-reduced receptor species of Mr355K, 285K and small amounts of 427K and 182K. Although different non-reduced receptor species were evident depending on the adipocyte receptor preparation (e.g. isolated adipocytes or fat cell membranes), no differences were found between obese and lean controls or between subcutaneous and omental receptors when the appropriate comparisons were made. Upon sulphydryl reduction, all receptor preparations had a major binding subunit of 125K Mr. In conclusion, obesity is characterized by a dilution of the insulin receptor over the adipocyte cell surface in the absence of a change in total cellular content of receptors. The difference in insulin binding affinities between omental and subcutaneous adipocytes could not be explained by an alteration in receptor molecular weight.