Hinds Louise, Green Judith L, Knuepfer Ellen, Grainger Munira, Holder Anthony A
Division of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, UK.
Eukaryot Cell. 2009 Dec;8(12):1869-79. doi: 10.1128/EC.00218-09. Epub 2009 Oct 9.
We have identified a new Plasmodium falciparum erythrocyte binding protein that appears to be located in the micronemes of the merozoite stage of the parasite and membrane linked through a glycosylphosphatidylinositol (GPI) anchor. The protein is designated GPI-anchored micronemal antigen (GAMA) and was identified by applying a set of selection criteria to identify previously uncharacterized merozoite proteins that may have a role in cell invasion. The protein is also present in the proteomes of the sporozoite and ookinete micronemes and is conserved throughout the genus. GAMA contains a novel domain that may be constrained by disulfide bonds and a predicted C-terminal hydrophobic sequence that is presumably replaced by the GPI. The protein is synthesized late during schizogony, processed into two fragments that are linked by a disulfide bond, and translocated to an apical location, which is probably the micronemes. In a proportion of free merozoites GAMA can also be detected on the parasite surface. Following erythrocyte invasion the bulk of the protein is shed in a soluble form, although a short C-terminal fragment may be carried into the newly invaded red blood cell. The protein was shown to bind reversibly to erythrocytes and therefore represents a new example of a host cell binding protein.
我们鉴定出一种新的恶性疟原虫红细胞结合蛋白，它似乎位于疟原虫裂殖子阶段的微线体中，并通过糖基磷脂酰肌醇（GPI）锚定与膜相连。该蛋白被命名为GPI锚定微线体抗原（GAMA），是通过应用一组选择标准来鉴定的，这些标准用于识别可能在细胞入侵中起作用的先前未表征的裂殖子蛋白。该蛋白也存在于子孢子和动合子微线体的蛋白质组中，并且在整个属中都保守。GAMA包含一个可能受二硫键限制的新结构域和一个预测的C末端疏水序列，该序列可能被GPI取代。该蛋白在裂体增殖后期合成，加工成通过二硫键连接的两个片段，并转运到顶端位置，可能是微线体。在一部分游离裂殖子中，也可以在寄生虫表面检测到GAMA。红细胞入侵后，大部分蛋白以可溶形式脱落，尽管一个短的C末端片段可能会被带入新入侵的红细胞中。该蛋白被证明能与红细胞可逆结合，因此代表了一种宿主细胞结合蛋白的新例子。
