蓝氏贾第鞭毛虫中一种富含半胱氨酸蛋白的抗原变异
Antigenic variation of a cysteine-rich protein in Giardia lamblia.
作者信息
Adam R D, Aggarwal A, Lal A A, de La Cruz V F, McCutchan T, Nash T E
机构信息
Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
出版信息
J Exp Med. 1988 Jan 1;167(1):109-18. doi: 10.1084/jem.167.1.109.
The WB isolate of Giardia lamblia expresses a cysteine-rich 170-kD surface antigen (CRP170) that undergoes antigenic variation. An (6E7), cytotoxic for isolates expressing CRP170, was used in another study to select antigenic variants from clones of the WB isolate of Giardia. CRP170 was replaced by surface-labeled bands ranging in size from approximately 50 to 170 kD. In this study, mAb 6E7 was used to isolate a 1-kb portion of the CRP170 gene (M2-1) from a lambda gt 11 expression library. The M2-1 clone hybridized to a 5.4-kb transcript from isolates expressing CRP170 but did not hybridize to RNA from antigenic variants. Evidence was found for frequent rearrangements at the CRP170 gene locus. DNA sequencing of the M2-1 clone revealed the presence of long tandem repeats. The putative amino acid sequence of M2-1 reveals a 12% cysteine content, and CRP170 is readily labeled in vivo with cysteine.
蓝氏贾第鞭毛虫的WB分离株表达一种富含半胱氨酸的170-kD表面抗原（CRP170），该抗原会发生抗原变异。在另一项研究中，使用对表达CRP170的分离株具有细胞毒性的单克隆抗体（6E7）从蓝氏贾第鞭毛虫WB分离株的克隆中筛选抗原变异体。CRP170被大小约为50至170 kD的表面标记条带所取代。在本研究中，单克隆抗体6E7用于从λgt 11表达文库中分离CRP170基因的1-kb片段（M2-1）。M2-1克隆与表达CRP170的分离株的5.4-kb转录本杂交，但不与抗原变异体的RNA杂交。发现CRP170基因位点存在频繁重排的证据。M2-1克隆的DNA测序揭示了长串联重复序列的存在。M2-1的推定氨基酸序列显示半胱氨酸含量为12%，并且CRP170在体内很容易被半胱氨酸标记。
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