Burnett R C, Schneiderman R D, Knight K L
Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago.
Adv Exp Med Biol. 1987;216A:15-22. doi: 10.1007/978-1-4684-5344-7_3.
Screening of recombinant cosmid and phage libraries with a rabbit C alpha cDNA probe has identified a total of seven C alpha genes organized into two clusters; one cluster contains four genes and the other cluster, three genes. Southern blot analysis of genomic DNA indicates that the rabbit genome contains a minimum of ten C alpha genes; at least three genes remain to be cloned. Four of the seven cloned C alpha genes have been tested for their ability to be expressed in vitro. Each gene was cloned 3' to a rearranged murine VDJ gene, and the chimeric gene was then transfected into J558L plasmacytoma cells. Stable transfectants were selected, and each transfectoma was shown to express a chimeric alpha-heavy chain. These chimeric alpha-heavy chains were of two sizes, 55 kd and 60 kd. Each of the four transfectomas secreted chimeric heavy chains in association with endogenous murine lambda light chains. All four C alpha genes tested were expressible, indicating that the rabbit may have multiple IgA subclasses or isotypes. This is in marked contrast to mouse and human which have only one and two subclasses of IgA, respectively.
用兔Cα cDNA探针筛选重组黏粒和噬菌体文库，共鉴定出7个Cα基因，它们组成两个簇；一个簇包含4个基因，另一个簇包含3个基因。基因组DNA的Southern印迹分析表明，兔基因组至少包含10个Cα基因；至少还有3个基因有待克隆。已对7个克隆的Cα基因中的4个进行了体外表达能力测试。每个基因都克隆到重排的鼠VDJ基因的3'端，然后将嵌合基因转染到J558L浆细胞瘤细胞中。筛选出稳定的转染子，每个转染瘤均显示表达嵌合α重链。这些嵌合α重链有两种大小，55kd和60kd。4个转染瘤中的每一个都分泌与内源性鼠λ轻链相关的嵌合重链。测试的所有4个Cα基因均可表达，表明兔可能有多个IgA亚类或同种型。这与小鼠和人类形成鲜明对比，小鼠和人类分别只有1个和2个IgA亚类。
