Martin R M, Gasser R B, Jones M K, Lightowlers M W
University of Melbourne, Department of Veterinary Science, Werribee, Victoria, Australia.
Mol Biochem Parasitol. 1995 Mar;70(1-2):139-48. doi: 10.1016/0166-6851(95)00020-2.
A muscle-specific gene of Echinococcus granulosus has been identified and characterized. A lambda gt11 clone (10P1), containing an incomplete copy of the gene, was originally isolated from a larval E. granulosus cDNA library by serum antibodies from dogs infected with the parasite. The full-length cDNA sequence was obtained by PCR amplification of cDNA from an adult E. granulosus lambda gt22A library. Southern blot analysis indicated the presence of the gene as a single copy in the genome of E. granulosus and also detected homologous genes in genomic DNA of E. multilocularis and Taenia saginata. The 21.2-kDa protein deduced from the complete cDNA sequence contains two regions of 12 amino acids with similarity to the EF-hand motif of calcium binding proteins. Antibodies raised against the purified 10P1-GST fusion protein detected a 22-kDa antigen in the E. granulosus developmental stages examined. Immunoelectron microscopy localized the native protein in the muscle of the parasite. The amino-acid sequence of the E. granulosus protein shows significant homology to the muscle proteins mp20 of Drosophila melanogaster, chicken SM22 alpha and mammalian calponin, and also to the neuronal protein NP25 of rats. A conserved carboxy-terminal motif of 17 amino acids is present in all the homologous proteins and is proposed to be the characteristic feature of a novel protein family. The term myophilin is proposed for the E. granulosus protein due to its localization and homology to other muscle proteins.
细粒棘球绦虫的一个肌肉特异性基因已被鉴定和表征。一个λgt11克隆（10P1），包含该基因的一个不完整拷贝，最初是从感染该寄生虫的犬血清抗体从细粒棘球绦虫幼虫cDNA文库中分离得到的。通过对成年细粒棘球绦虫λgt22A文库的cDNA进行PCR扩增获得了全长cDNA序列。Southern印迹分析表明该基因在细粒棘球绦虫基因组中以单拷贝形式存在，并且在多房棘球绦虫和牛带绦虫的基因组DNA中也检测到了同源基因。从完整cDNA序列推导的21.2 kDa蛋白包含两个12个氨基酸的区域，与钙结合蛋白的EF手基序相似。针对纯化的10P1-GST融合蛋白产生的抗体在检测的细粒棘球绦虫发育阶段中检测到一种22 kDa的抗原。免疫电子显微镜将天然蛋白定位在寄生虫的肌肉中。细粒棘球绦虫蛋白的氨基酸序列与果蝇的肌肉蛋白mp20、鸡的SM22α和哺乳动物的钙调蛋白以及大鼠的神经元蛋白NP25具有显著同源性。所有同源蛋白中都存在一个由17个氨基酸组成的保守羧基末端基序，被认为是一个新蛋白家族的特征。由于细粒棘球绦虫蛋白的定位及其与其他肌肉蛋白的同源性，建议将其命名为肌亲和蛋白。
