Yoshida N, Potocnjak P, Nussenzweig V, Nussenzweig R S
J Exp Med. 1981 Oct 1;154(4):1225-36. doi: 10.1084/jem.154.4.1225.
In a previous paper (2) we identified a protective antigen (Pb44) of the surface membrane of sporozoites of Plasmodium berghei by means of a monoclonal antibody. Immunoprecipitation of extracts of mature salivary gland sporozoites, metabolically labeled with L[35S]methionine using the same monoclonal antibody, revealed three specific polypeptides: *Pb44, *Pb52, and *Pb54. Metabolically labeled *Pb44 is probably identical to the protective antigen previously identified by surface labeling. Both proteins have the same molecular weights and isoelectric points under denaturing conditions, and they share an epitope. Moreover, *Pb44 also seems to be located on the cell membrane. The results of pulse-chase experiments strongly suggest that *Pb52 is the precursor of *Pb44. The relationship between *Pb54 and the protective antigen is unknown. The three polypeptides seem to be strictly associated with only one of the developmental stage of the parasite. They were not detected in blood forms and were found in minute amounts in sporozoites from the midgut of mosquitoes. In contrast, in mature salivary gland sporozoites they constitute main products of protein synthesis.
在之前的一篇论文（2）中，我们借助单克隆抗体鉴定出了伯氏疟原虫子孢子表面膜的一种保护性抗原（Pb44）。使用同一单克隆抗体对用L[35S]甲硫氨酸进行代谢标记的成熟唾液腺子孢子提取物进行免疫沉淀，揭示出三种特异性多肽：Pb44、Pb52和Pb54。经代谢标记的Pb44可能与先前通过表面标记鉴定出的保护性抗原相同。在变性条件下，这两种蛋白质具有相同的分子量和等电点，并且它们共享一个表位。此外，Pb44似乎也位于细胞膜上。脉冲追踪实验结果强烈表明Pb52是*Pb44的前体。*Pb54与保护性抗原之间的关系尚不清楚。这三种多肽似乎仅与寄生虫的一个发育阶段严格相关。在血期未检测到它们，而在蚊子中肠的子孢子中含量极少。相比之下，在成熟唾液腺子孢子中，它们是蛋白质合成的主要产物。
