Characterization of (3H)cytochalasin B binding to the fat cell plasma membrane.
Characterization of (3H)cytochalasin B binding to the fat cell plasma membrane.
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(3H)细胞松弛素 B 与脂肪细胞质膜结合的表征。
DOI：
10.1016/s0021-9258(17)33476-2
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
M. Czech
中科院分区：
文献类型：
--
作者：
M. Czech
细胞松弛素B、双嘧达莫或根皮苷可明显抑制D-[3 H]脱氧葡萄糖和D-[3 H]葡萄糖经纯化脂肪细胞质膜的转运。L-[3 H]葡萄糖摄取速率显著减慢，且不受细胞松弛素B的影响。Ca ~（2+）或Mg ~（2+）的存在显著增强了[~ 3 H]细胞松弛素B与脂肪细胞质膜的结合率及其与膜的解离率。[~ 3 H]细胞松弛素B与脂肪细胞膜结合的Scatchard图分析表明存在高亲和力和低亲和力位点，其表观解离常数分别约为6 × 10 ~（-7）M和5 × 10 ~（-6）M。半最大抑制D-葡萄糖转运的细胞松弛素B的浓度约为5 × 10（-7）M，表明高亲和力位点参与转运抑制。浓度高达100 mM的D-葡萄糖对[3 H]细胞松弛素B与这些高亲和力位点的结合没有影响，而转运抑制剂根皮苷、根皮素和双嘧达莫显著抑制这种结合。蛋白质试剂N-乙基马来酰亚胺、2-羟基-5-硝基苄基溴、1-氟-2，4-二硝基苯、二硫苏糖醇和胰蛋白酶也降低结合。超声分散提取的脂肪细胞质膜脂质不结合[3 H]细胞松弛素B，也不通过细胞松弛素B敏感途径摄取葡萄糖。结果表明，细胞松弛素B抑制己糖转运脂肪细胞继发于其与膜蛋白位点的相互作用，不同于那些结合D-葡萄糖。
Transport of D-[3H]deoxyglucose and D-[3H]glucose by purified fat cell plasma membranes was markedly inhibited by cytochalasin B,dipyridamole, or phlorizin. The rate of L-[3H]glucose uptake was significantly slower and was unaffected by cytochalasin B. Both the rates of association of [3H]cytochalasin B with the fat cell plasma membrane and its dissociation from the membrane was significantly enhanced by the presence of Ca2+ or Mg2+. Scatchard plot analysis of [3H]cytochalasin B binding to fat cell membranes indicated the presence of high affinity and low affinity sites which exhibited apparent dissociation constants of about 6 X 10(-7) M and 5 X 10(-6) M, respectively. The concentration of cytochalasin B which half-maximally inhibited D-glucose transport was about 5 X 10(-7) M, indicating the high affinity sites are involved in transport inhibition. D-Glucose at concentrations as high as 100 mM had no effect on the binding of [3H]cytochalasin B to these high affinity sites, while the transport inhibitors phlorizin, phloretin, and dipyridamole markedly inhibited this binding. The protein reagents N-ethylmaleimide, 2-hydroxy-5-nitrobenzylbromide, 1-fluoro-2,4-dinitrobenzene, dithiothreitol, and trypsin also reduced binding. Extracted fat cell plasma membrane lipids dispersed by sonication did not bind [3H]cytochalasin B nor take up glucose by a cytochalasin B-sensitive pathway. The results indicate that cytochalasin B inhibits hexose transport in fat cells secondary to its interaction with membrane protein sites distinct from those which bind D-glucose.