Rangarajan D, Gokool S, McCrossan M V, Smith D F
Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, UK.
J Cell Sci. 1995 Nov;108 ( Pt 11):3359-66. doi: 10.1242/jcs.108.11.3359.
The stage specific Gene B protein (GBP) of Leishmania major localises to the surface of infective metacyclic parasites, where it associates with the developmentally regulated surface glycoconjugate, lipophosphoglycan (LPG). This association has been proposed to aid maintenance of GBP on the parasite surface. In this paper, we show that the abundance of GBP on the extracellular metacyclic cell surface is in the order of 100,000 copies per cell. This level of expression is comparable to that seen in the intracellular amastigote stage, in which GBP is also localised to the surface, despite the lack of metacyclic stage specific LPG. Furthermore GBP expressed from an episome in avirulent parasites, which are unable to synthesise metacyclic LPG or endogenous GBP, also localises to the parasite surface. These data demonstrate that GBP can maintain a surface localisation in the absence of metacyclic LPG, suggesting that it is able to associate with other glycoconjugates on the surface of infective parasites.
硕大利什曼原虫的阶段特异性基因B蛋白（GBP）定位于感染性循环后期寄生虫的表面，在那里它与发育调控的表面糖缀合物——脂磷酸聚糖（LPG）相关联。有人提出这种关联有助于GBP在寄生虫表面的维持。在本文中，我们表明细胞外循环后期细胞表面GBP的丰度约为每个细胞100,000个拷贝。这种表达水平与细胞内无鞭毛体阶段所见的水平相当，在该阶段GBP也定位于表面，尽管缺乏循环后期阶段特异性LPG。此外，从无毒寄生虫的附加体表达的GBP，这些寄生虫无法合成循环后期LPG或内源性GBP，也定位于寄生虫表面。这些数据表明，在没有循环后期LPG的情况下，GBP可以维持表面定位，这表明它能够与感染性寄生虫表面的其他糖缀合物相关联。
