CHICKEN IGL VARIABLE REGION GENE CONVERSIONS DISPLAY PSEUDOGENE DONOR PREFERENCE AND 5' TO 3' POLARITY
CHICKEN IGL VARIABLE REGION GENE CONVERSIONS DISPLAY PSEUDOGENE DONOR PREFERENCE AND 5' TO 3' POLARITY
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DOI：
10.1101/gad.4.4.548
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发表时间：
1990-04-01
影响因子：
10.5
通讯作者：
THOMPSON, CB
中科院分区：
文献类型：
--
作者：
MCCORMACK, WT;THOMPSON, CB
鸡免疫球蛋白可变区多样性是在法氏囊中B细胞发育期间通过染色体内基因转换产生的，导致独特重排的VL1和VH1基因内的序列块被来自V区假基因区段（ψ V）的同源序列取代。在这份报告中，217个基因转换事件在52个随机克隆的核苷酸序列进行了分析，以表征基因转换的分子机制。 作为基因转化供体的ψ VL的使用频率显示取决于ψ VL区段与VL1的接近度、与VL1的同源性程度和ψ VL区段的相对取向。在VL片段和VL 1之间的同源性5 ″区中没有观察到基因转换事件，但分布在VL 1外显子的整个剩余部分中。单个基因转换事件的5“末端总是开始于供体VL和受体VL 1基因之间的同源性区域，而3”末端可以出现在非同源性区域，并且通常具有核苷酸插入或缺失。这些结果表明在基因转换机制中存在5“到3”的极性。我们的数据的影响进行了讨论，目前的基因转换的分子模型。
Chicken immunoglobulin variable region diversity is generated during B-cell development in the bursa of Fabricius by intrachromosomal gene conversion, resulting in the replacement of sequence blocks within the unique rearranged VL1 and VH1 genes with homologous sequences derived from V region pseudogene segments (.PSI.V). In this report, the nucleotide sequences of 217 gene conversion events in 52 random IgL clones were analyzed to characterize the molecular mechanism of gene conversion. The frequency of .psi.VL usage as gene conversion donors is shown to depend on the proximity of the .psi.VL segment to VL1, extent of homology with VL1, and relative orientation of the .psi.VL segments. Gene conversion events are not observed in the 5'' region of homology between .psi.VL segments and VL1, but are distributed throughout the remainder of the VL1 exon. The 5'' ends of individual gene conversion events always begin in regions of homology between the donor .psi.VL and recipient VL1 gene, whereas the 3'' ends can occur in regions of nonhomology and often have nucleotide insertions or deletions. These results suggest a 5'' to 3'' polarity in the gene conversion mechanism. The implications of our data are discussed in relation to current molecular models of gene conversion.