Unusually long germline DH genes contribute to large sized CDR3H in bovine antibodies
Unusually long germline DH genes contribute to large sized CDR3H in bovine antibodies
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DOI：
10.1016/s0161-5890(03)00098-1
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发表时间：
2003-09-01
影响因子：
3.6
通讯作者：
Kaushik, AK
中科院分区：
文献类型：
--
作者：
Shojaei, F;Saini, SS;Kaushik, AK
我们早先证明了在牛的一些功能性IgM抗体中存在异常长的重链第三互补决定区（CDR 3 H）（多达61个氨基酸（aa）），具有多个半胱氨酸残基。为了了解如此长的CDR 3 H的起源。我们现在已经鉴定了牛的生殖系多样性基因（D-H）。用一种新开发的DNA探针与牛DH基因序列杂交，分离、克隆了一个2.3kb的基因组DNA片段，并测定了其核苷酸序列。核苷酸序列的检查导致三个不同大小的牛生殖系D-H基因片段的鉴定：42 bp（14个可能的密码子）。58 bp（19个可能的密码子）和148 bp（49个可能的密码子）。特征性重复GGT和达特密码子，在可能由生殖系基因编码的胎儿VDJ重排的CDR 3 H区域中显著，在两个鉴定的生殖系D-H基因中注意到。这些D-H基因优先在第三个阅读框中表达，以编码CDR 3 H区中的亲水性甘氨酸和酪氨酸残基。系统发育分析表明，牛的D-H基因与兔和鸡的D-H基因最接近。因此，牛中存在短和长种系D-H基因，并且这些基因能够直接导致CDR 3 H大小异质性，包括特别长的CDR 3 H区域。除了与重组相关的机械因素之外。(C)2003爱思唯尔科技有限公司版权所有。
We demonstrated earlier the existence of an exceptionally long third complementarity-determining region of the heavy chain (CDR3H) (up to 61 amino acids (aa)), with multiple cysteine residues, in some functional IgM antibodies of cattle. To understand the origin of such a long CDR3H. we have now characterized the germline diversity gene (D-H) of the cattle. A 2.3 kb genomic DNA fragment hybridizing with a newly developed DNA probe to putative bovine DH gene sequences was isolated, cloned and its nucleotide sequence determined. Inspection of the nucleotide sequence led to identification of three bovine germline D-H gene segments of varying size: 42 bp (14 possible codons). 58 bp (19 possible codons) and 148 bp (49 possible codons). The characteristic repetitive GGT and TAT codons, remarkable in the CDR3H region of fetal VDJ rearrangements likely encoded by germline genes, are noted in two of the identified germline D-H genes. These D-H genes are preferentially expressed in the third reading frame to encode hydrophilic glycine and tyrosine residues in the CDR3H region. Phylogenetic analysis suggests that bovine D-H genes are closest to rabbit and chicken D-H genes. Thus, both short and long germline D-H genes exist in cattle and these are capable of directly contributing to CDR3H size heterogeneity including the exceptionally long CDR3H region. apart from recombination associated mechanistic factors. (C) 2003 Elsevier Science Ltd. All rights reserved.