Snow J W, Vincentelli J, Brandts J F
Biochim Biophys Acta. 1981 Apr 6;642(2):418-28. doi: 10.1016/0005-2736(81)90457-0.
Scanning microcalorimetry was employed as an aid in examining some structural features of the anion transport system in red blood cell vesicles. Two structural transitions were previously shown to be sensitive to several covalent and non-covalent inhibitors of anion transport in red cells. In this study, these transitions were selectively removed, either thermally or enzymatically, and the subsequent effect on 35SO2- 4 efflux in red cell vesicles was determined. It is shown that removal of one of these transitions (B2) has a negligible inhibitory effect on anion transport. Cytoplasmic, intermolecular disulfide linkages between band 3 dimers are known to form during the B2 transition. The integrity of the 4,4-diisothiocyanostilbene-2,2-disulfonate-sensitive C transition, on the other hand, is shown to be a requirement for anion transport. The localized region of the membrane giving rise to this transition contains the transmembrane segment of band 3, as well as membrane phospholipids. The calorimetric results suggest a structure of band 3 which involves independent structural domains, and are consistent with the transmembrane segment playing a direct role in the transport process.
扫描量热法被用于辅助研究红细胞囊泡中阴离子转运系统的一些结构特征。先前已表明，两种结构转变对红细胞中几种阴离子转运的共价和非共价抑制剂敏感。在本研究中，这些转变通过热或酶促方式被选择性去除，并测定了随后对红细胞囊泡中35SO2- 4流出的影响。结果表明，去除其中一种转变（B2）对阴离子转运的抑制作用可忽略不计。已知在B2转变过程中会形成带3二聚体之间的细胞质分子间二硫键。另一方面，4,4-二异硫氰基芪-2,2-二磺酸盐敏感的C转变的完整性被证明是阴离子转运的必要条件。产生这种转变的膜局部区域包含带3的跨膜片段以及膜磷脂。量热结果表明带3的结构涉及独立的结构域，并且与跨膜片段在转运过程中发挥直接作用一致。
