Ngô H M, Bouck G B
Department of Biological Sciences (m/c 066), University of Illinois at Chicago 60607-7080, USA.
J Eukaryot Microbiol. 1998 May-Jun;45(3):323-33. doi: 10.1111/j.1550-7408.1998.tb04543.x.
The emergent flagellum of euglenoids and trypanosomatids contained in addition to microtubules a prominent filamentous structure--the flagellar rod (paraflagellar/paraxonemal rod). Immunoblots and immunofluorescence localization using three antibodies generated against gel-isolated proteins confirmed previous studies that the Euglena flagellar rod consisted of polypeptides migrating at 66-, 69-, and 75-kD. Immunoblotting after two dimensional gel electrophoresis identified ten or more isoforms of these polypeptides. Differences in migration in acrylamide gels under nonreducing and reducing conditions suggested that the rod proteins contain intramolecular disulfide linkages. Comparative peptide mapping showed that the 66-, 69-, and 75-kD polypeptides were distinct, but related proteins, and also identified a fourth related protein migrating at 64-kD. Using antibodies against rod proteins, two overlapping cDNAs were isolated and from their sequences the cDNAs were predicted to encode 334 amino acids of the 66-kD protein; the amino acid sequence had > 65% identity to the carboxyl-terminus of the trypanosomatid flagellar rod proteins. Secondary structural prediction suggested that flagellar rod proteins contain an extended segmented coiled coil stalk and two nonhelical heads. Coiled coil appeared to be an important structural motif in the construction of flagellar rod filaments.
眼虫类和锥虫类的应急鞭毛除微管外还包含一种突出的丝状结构——鞭杆（副鞭毛/轴旁杆）。使用针对凝胶分离蛋白产生的三种抗体进行免疫印迹和免疫荧光定位，证实了先前的研究，即眼虫的鞭杆由迁移率为66、69和75 kDa的多肽组成。二维凝胶电泳后的免疫印迹鉴定出这些多肽有十种或更多种同工型。在非还原和还原条件下丙烯酰胺凝胶中迁移的差异表明鞭杆蛋白含有分子内二硫键。比较肽图显示66、69和75 kDa的多肽是不同但相关的蛋白质，还鉴定出一种迁移率为64 kDa的第四种相关蛋白质。使用针对鞭杆蛋白的抗体，分离出两个重叠的cDNA，根据其序列预测这些cDNA编码66 kDa蛋白质的334个氨基酸；该氨基酸序列与锥虫鞭杆蛋白的羧基末端有>65%的同一性。二级结构预测表明鞭杆蛋白包含一个延伸的分段卷曲螺旋柄和两个非螺旋头部。卷曲螺旋似乎是鞭杆丝构建中的一个重要结构基序。
