Soltys B J, Gupta R S
Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada.
J Parasitol. 1994 Aug;80(4):580-90.
Giardia lamblia trophozoites contain a 60-kDa protein recognized in immunoblots by antibody to mammalian hsp60, a protein localized in mitochondria in eukaryotic cells. The cellular distribution of this protein is evaluated by immunofluorescence microscopy using monoclonal antibody to human hsp60, polyclonal antibody to rodent hsp60, and 2 monoclonal antibodies to mycobacterial 65-kDa antigen, a prokaryotic hsp60 homolog. All of these antibodies, except 1, which is specific for prokaryotic hsp60, give a punctate labeling pattern throughout the cytoplasm, indicating that the 60-kDa protein is concentrated at discrete sites in the cytoplasm. The polyclonal hsp60 antiserum reveals additional punctate labeling colocalized on axonemes of the anterior flagella. Postembedment immunogold labeling and electron microscopy confirm that the antigen is clustered at foci in the cytoplasm but show no evidence of association with a membranous organelle. The hsp60 reactivity is also observed on anterior axonemes within the cytoplasm and on the adhesive disc. Hoechst 33258 DNA staining as well as electron microscopy give no evidence of endosymbionts, so a false positive due to a prokaryotic hsp60 homolog is unlikely. The presence of an hsp60-related protein in G. lamblia raises interesting questions concerning its origin.
蓝氏贾第鞭毛虫滋养体含有一种60 kDa的蛋白质，在免疫印迹中可被抗哺乳动物hsp60的抗体识别，hsp60是一种定位于真核细胞线粒体中的蛋白质。使用抗人hsp60的单克隆抗体、抗啮齿动物hsp60的多克隆抗体以及抗分枝杆菌65 kDa抗原（一种原核hsp60同源物）的两种单克隆抗体，通过免疫荧光显微镜评估该蛋白质的细胞分布。除了一种对原核hsp60具有特异性的抗体外，所有这些抗体在整个细胞质中均呈现点状标记模式，表明60 kDa的蛋白质集中在细胞质中的离散位点。多克隆hsp60抗血清显示在前鞭毛的轴丝上有额外的点状标记共定位。包埋后免疫金标记和电子显微镜证实该抗原聚集在细胞质中的焦点处，但未显示与膜性细胞器相关的证据。在细胞质内的前轴丝以及粘附盘上也观察到hsp60反应性。Hoechst 33258 DNA染色以及电子显微镜均未发现内共生体的证据，因此不太可能是由于原核hsp60同源物导致的假阳性。蓝氏贾第鞭毛虫中存在与hsp60相关的蛋白质引发了有关其起源的有趣问题。
