Noe A R, Adams J H
Department of Biological Sciences, University of Notre Dame, Indiana, USA.
Mol Biochem Parasitol. 1998 Oct 30;96(1-2):27-35. doi: 10.1016/s0166-6851(98)00084-x.
We have previously cloned genes from multiple rodent malaria species exhibiting characteristics of the genes encoding Duffy binding like-erythrocyte binding proteins (DBL-EBP). Homology is seen in the intron/exon structure of the genes and in the carboxyl terminal region (including the deduced carboxyl cysteine-rich domain) of the proteins they encode. However, the amino termini of these proteins are not homologous to the DBL-EBP but contain tandem cysteine-rich regions that are similar to the cysteine-rich region of AMA-1 (apical membrane antigen-1), a rhoptry protein. This new family of proteins has been termed MAEBL and these are paralogues of both AMA-1 and the DBL-EBP. Serum against the carboxyl cysteine-rich region of the Plasmodium yoelii YM MAEBL reacted to parasites with a punctate fluorescence pattern characteristic of apical organelle proteins and also localized MAEBL to the surface of merozoites within schizonts. This antiserum immunoprecipitated a protein doublet (120/128 kDa) that was unexpectedly insoluble when compared to members of the DBL-EBP. Characterization of MAEBL was extended through colocalization studies comparing the P. yoelii YM MAEBL to other parasite proteins. This protein appeared to be located in the rhoptry organelles as it colocalized with both AMA-1 and the P. yoelii 235 kDa rhoptry proteins within parasites. In addition, MAEBL is expressed relatively early in schizont development and appears on the merozoite surface after segmentation. Both the pattern and time of expression of the P. yoelii YM MAEBL are consistent with a rhoptry rather than a microneme protein.
我们之前已经从多种啮齿动物疟原虫物种中克隆了基因，这些基因表现出编码达菲结合样红细胞结合蛋白（DBL-EBP）的基因特征。在这些基因的内含子/外显子结构以及它们所编码蛋白质的羧基末端区域（包括推导的富含羧基半胱氨酸结构域）中可以看到同源性。然而，这些蛋白质的氨基末端与DBL-EBP并不同源，但含有与AMA-1（顶膜抗原-1）的富含半胱氨酸区域相似的串联富含半胱氨酸区域，AMA-1是一种棒状体蛋白。这个新的蛋白质家族被命名为MAEBL，它们是AMA-1和DBL-EBP的旁系同源物。针对约氏疟原虫YM MAEBL富含羧基半胱氨酸区域的血清与具有顶细胞器蛋白特征性点状荧光模式的寄生虫发生反应，并且还将MAEBL定位到裂殖体内裂殖子的表面。该抗血清免疫沉淀出一种蛋白双条带（120/128 kDa），与DBL-EBP成员相比，该双条带出人意料地不溶。通过将约氏疟原虫YM MAEBL与其他寄生虫蛋白进行共定位研究，扩展了对MAEBL的表征。这种蛋白质似乎位于棒状体细胞器中，因为它在寄生虫体内与AMA-1和约氏疟原虫235 kDa棒状体蛋白都共定位。此外，MAEBL在裂殖体发育的相对早期表达，并在分裂后出现在裂殖子表面。约氏疟原虫YM MAEBL的表达模式和时间都与棒状体蛋白而非微线体蛋白一致。
