High affinity cytochalasin B binding to red cell membrane proteins which are unrelated to sugar transport.
High affinity cytochalasin B binding to red cell membrane proteins which are unrelated to sugar transport.
复制标题
高亲和力细胞松弛素 B 与与糖转运无关的红细胞膜蛋白结合。
DOI：
10.1016/s0021-9258(19)63373-9
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发表时间：
1977
期刊：
影响因子：
--
通讯作者：
C. E. Snyder
中科院分区：
文献类型：
--
作者：
S. Lin;C. E. Snyder
在人、牛和兔的红细胞中发现了高亲和力的细胞松弛素B结合位点，显然与糖运输无关。这些位点位于暴露于细胞膜细胞质一侧的膜蛋白上。它们不与D-葡萄糖结合，但与细胞松弛素A、B、C、D、E和二氢细胞松弛素B结合。与糖运输相关的细胞松弛素B结合位点不同，这些位点不敏感，但当红细胞膜在37℃下孵育2小时，或用二甲基马来酸酐或EDTA提取时，它们会丢失。细胞松弛素B与这些位点的结合是快速和可逆的，在4”，23”和37”，并通过低pH和高离子强度增强。平衡条件下获得的结合数据的Scatchard图分析表明，细胞松弛素b受体复合物的解离常数为1至2 × 10eR M，每个人或牛红细胞有4至5 × lo4个位点。这些位点仅占人类红细胞中高亲和力细胞松弛素B结合位点总数的一小部分。然而，它们代表了牛和兔红细胞中存在的所有高亲和力位点，它们缺乏与人类红细胞相似的糖运输系统。这种结合位点在红细胞中的生物学功能尚不清楚。然而，由于它们结合细胞松弛素B和二氢细胞松弛素B这两种影响细胞运动和形态的化合物，我们假设这些结合位点可能与收缩蛋白有关。细胞松弛素B对哺乳动物细胞的大多数生物学作用可分为两类。在较低浓度（10 -6 M）下，药物抑制小分子（即己糖和核苷）穿过细胞膜的运输（Kletzien et al., 1972; Plagemann and Estensen, 1972）。在较高的浓度下（10 - 4 M），药物会影响细胞的运动和形态（Wessells et al., 1971）。我们之前报道过，哺乳动物细胞有两类细胞松弛素B的结合位点：高亲和力位点，解离常数（K,）为~ 10~ M，低亲和力位点，KD为rlO+ M （Lin et aZ., 1974）。在
High affinity cytochalasin B binding sites which are apparently unrelated to sugar transport have been found in human, bovine, and rabbit red blood cells. These sites are located on membrane proteins which are exposed to the cytoplasmic side of the cell membrane. They do not bind D-glucose, but bind cytochalasins A, B, C, D, E, and dihydrocytochalasin B. Unlike sugar transport-related cytochalasin B binding sites, these sites are not sensitive top-chloromercuribenzoate, but are lost when red cell membranes are incubated at 37” for 2 h, or extracted with dimethyl maleic anhydride or EDTA. The binding of cytochalasin B to these sites ig rapid and reversible at 4”, 23”, and 37”, and is enhanced by low pH and high ionic strength. Scatchard plot analysis of binding data obtained under equilibrium conditions shows that the dissociation constant of the cytochalasin B. receptor complex is 1 to 2 x 10eR M and that there are 4 to 5 x lo4 sites per human or bovine red cell. These sites represent only a small fraction of the total number of high affinity cytochalasin B binding sites in the human red cell. However, they represent all of the high affinity sites present in bovine and rabbit red cells, which lack a sugar transport system similar to that found in human red cells. The biological function of this type of binding site in the red cell is not known. However, because they bind both cytochalasin B and dihydrocytochalasin B, compounds which affect cell motility and morphology, we postulate that these binding sites may be associated with contractile proteins.Most of the biological effects of cytochalasin B on mammalian cells fall into one of two categories. At lower concentrations (lOme to 1O-6 M), the drug inhibits transport of small molecules (ie hexoses and nucleosides) across the cell membrane (Kletzien et al., 1972; Plagemann and Estensen, 1972). At higher concentrations (lo-” to 10e4 M), the drug affects cell motility and morphology (Wessells et al., 1971). We have previously reported that mammalian cells have two main classes of binding sites for cytochalasin B: high affinity sites with a dissociation constant (K,) of~ 10~’M and low affinity sites with a KD of rlO+ M (Lin et aZ., 1974). In the