Wong P
Institut de Recherches Cliniques de Montréal, Québec, Canada.
J Theor Biol. 1994 Nov 21;171(2):197-205. doi: 10.1006/jtbi.1994.1223.
A mechanism of control of erythrocyte shape, differing significantly from those previously proposed, is hypothesized. It was inferred from previous observations on the states of association of Band 3, the anion exchange protein. Its salient points are as follows. (i) The membrane skeleton is a pliable protein meshwork structure used to generate different erythrocyte shapes. (ii) Band 3 is a dodecamer bound by one of its subunits to ankyrin which is itself bound to the mid region of filamentous spectrin. (iii) Spectrin, by virtue of its high flexibility, folds and unfolds and its folding links the two actin protofilaments bound at its ends to Band 3 through the intermediary of Band 4.1 and glycophorin A. (iv) The alternate influx and efflux of anions mediated by Band 3 respectively folds and unfolds spectrin. (v) The ratio of Band 3 molecules with outward-facing conformation to those with inward-facing conformation controls the extents of folding of the skeleton spectrin molecules. This ratio is governed by the Gibbs-Donnan equilibrium ratio of anions and protons and by the Band 3 anion affinities and exchange rates.
本文提出了一种与先前提出的机制显著不同的红细胞形状控制机制。该机制是根据先前对阴离子交换蛋白带3（Band 3）结合状态的观察推断出来的。其要点如下：（i）膜骨架是一种柔韧的蛋白质网状结构，用于产生不同的红细胞形状。（ii）带3是一种十二聚体，其一个亚基与锚蛋白结合，而锚蛋白本身又与丝状血影蛋白的中部区域结合。（iii）血影蛋白由于其高度的柔韧性而折叠和展开，其折叠通过带4.1和血型糖蛋白A将两端结合的两条肌动蛋白原纤维与带3连接起来。（iv）由带3介导的阴离子的交替流入和流出分别使血影蛋白折叠和展开。（v）具有外向构象的带3分子与具有内向构象的带3分子的比例控制着骨架血影蛋白分子的折叠程度。该比例受阴离子和质子的吉布斯-唐南平衡比例以及带3阴离子亲和力和交换率的控制。
