Graeser R, Küry P, Franklin R M, Kappes B
Department of Structural Biology, University of Basel, Switzerland.
Mol Microbiol. 1997 Jan;23(1):151-9. doi: 10.1046/j.1365-2958.1997.2071571.x.
A mitogen-activated protein (MAP) kinase gene, PfMAP, from Plasmodium falciparum was recently identified. We expressed this gene in Escherichia coli to test whether it encodes a functional MAP kinase. Recombinant PfMAP kinase autophosphorylates on both the tyrosine and threonine residues within the TXY motif, and readily phosphorylates myelin basic protein as exogenous substrate. This identifies the PfMAP gene product as a true member of the growing family of MAP kinases. Wild-type PfMAP kinase expressed in COS-7 (SV40 transformed African green monkey kidney) cells seemed to induce apoptosis in these cells. Western blots and immunoprecipitations indicated that the kinase is expressed during the growth of the parasite in the red blood cell as three major forms: truncated forms with apparent molecular masses of 40 kDa and 80 kDa, and as a protein of approximately 150 kDa. The 40 kDa form is present throughout the intraerythrocytic development, whereas the two larger forms are only detected in mature parasites. The 40 kDa and 80 kDa forms are tyrosine phosphorylated, indicating that they represent the active forms of the PfMAP kinase. The total PfMAP kinase activity constantly increases with the maturation of the parasite.
最近在恶性疟原虫中鉴定出一种丝裂原活化蛋白（MAP）激酶基因PfMAP。我们在大肠杆菌中表达该基因，以测试它是否编码一种功能性MAP激酶。重组PfMAP激酶在TXY基序内的酪氨酸和苏氨酸残基上进行自身磷酸化，并容易将髓鞘碱性蛋白作为外源底物进行磷酸化。这确定了PfMAP基因产物是不断增加的MAP激酶家族中的一个真正成员。在COS-7（SV40转化的非洲绿猴肾）细胞中表达的野生型PfMAP激酶似乎在这些细胞中诱导凋亡。蛋白质免疫印迹和免疫沉淀表明，该激酶在寄生虫于红细胞内生长期间以三种主要形式表达：表观分子量为40 kDa和80 kDa的截短形式，以及一种约150 kDa的蛋白质。40 kDa形式在整个红细胞内发育过程中都存在，而两种较大的形式仅在成熟寄生虫中检测到。40 kDa和80 kDa形式是酪氨酸磷酸化的，表明它们代表PfMAP激酶的活性形式。PfMAP激酶的总活性随着寄生虫的成熟而不断增加。
