State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University Beijing, China.
Front Immunol. 2012 Dec 20;3:392. doi: 10.3389/fimmu.2012.00392. eCollection 2012.
The VH replacement process is a RAG-mediated secondary recombination in which the variable region of a rearranged VHDJH is replaced by a different germline VH gene. In almost all human and mouse VH genes, two sequence features appear to be crucial for VH replacement. First, an embedded heptamer, which is located near the 3' end of the rearranged VH gene, serves as a cryptic recombination signal sequence (3'cRSS) for the VH replacement process. Second, a short stretch of nucleotides located downstream of the 3'cRSS serve as a footprint of the original VH region, frequently encoding charged amino acids. In this review, we show that both of these two features are conserved in the VH genes of all jawed vertebrates, which suggests that the VH replacement process may be a conserved mechanism.
VH 替换过程是 RAG 介导的二次重组，在此过程中，重排的 VHDJH 的可变区被不同的胚系 VH 基因所取代。在几乎所有人类和小鼠的 VH 基因中，有两个序列特征似乎对 VH 替换至关重要。首先，一个嵌入的七聚体位于重排 VH 基因的 3'端附近，作为 VH 替换过程的隐蔽重组信号序列（3'cRSS）。其次，位于 3'cRSS 下游的一小段核苷酸作为原始 VH 区域的足迹，经常编码带电荷的氨基酸。在这篇综述中，我们表明，这两个特征在所有有颌脊椎动物的 VH 基因中都是保守的，这表明 VH 替换过程可能是一种保守的机制。
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