概括
研究人员确定了五个人类免疫球蛋白玛基因,包括一个伪基因. 玛3基因的发生.
科学领域:
- 免疫遗传学 免疫遗传学
- 分子生物学分子生物学
- 人类遗传学 人类遗传学
背景情况:
- 人类免疫球蛋白玛 (IGHG) 基因家族编码了适应性免疫力至关重要的抗体.
- 了解IGHG基因的结构和演变,可以了解免疫系统的多样性.
- 之前的研究已经特征了一些IGHG基因,但完整的家族结构和进化机制仍然不完全理解.
研究的目的:
- 从胎儿肝脏图书馆克隆和表征人类免疫球蛋白玛基因.
- 阐明IGHG基因家族多样化的进化历史和机制.
- 确定人类IGHG基因的基因组组织和相互关系.
主要方法:
- 从胎儿肝脏基因库中克隆人类免疫球蛋白玛基因.
- 克隆基因的核酸序列的确定.
- 链区域和基因组织的比较序列分析.
- 染色体步行来确定基因顺序和物理距离.
主要成果:
- 克隆了五个人类IGHG基因:四个编码已知的玛链 (玛1,玛2,玛3,玛4) 和一个伪基因.
- 玛3基因拥有四个链外基因,有证据表明它来自祖先的玛1和伪基因序列的混合起源,通过不平等的交叉.
- 马2基因位于马4基因上游19 kb处,建立了部分基因顺序.
结论:
- 人类IGHG基因家族通过多种DNA重组机制进化.
- 机制包括完整的基因重复,链外因子重复和通过不平等的交叉重组进行外因子重组.
- 这些发现为了解通过复杂的遗传事件来理解多基因家族的进化提供了一个模型.
相关概念视频
02:05Gene Evolution - Fast or Slow?
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
In contrast, regions which code...
01:57Gene Families
Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes are mistakenly duplicated during cell division. Unlike their parent genes (which are subject to selection pressure to maintain function), these gene copies do not need to preserve their sequences and may evolve at a relatively faster rate.
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
02:47Protein Families
Protein families are groups of homologous proteins; that is, they have similarities in amino acid sequences and three-dimensional structures. Protein families usually occur because of gene duplication, where an additional copy of a gene is inserted into the genome of an organism. Mutations that change the amino acids but still allow the protein to be properly synthesized, will lead to new protein family members. If these new proteins contain similar amino acids in key locations, protein...
01:57Gene Families
Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes are mistakenly duplicated during cell division. Unlike their parent genes (which are subject to selection pressure to maintain function), these gene copies do not need to preserve their sequences and may evolve at a relatively faster rate.
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
02:05Gene Evolution - Fast or Slow?
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
In contrast, regions which code...
02:47Protein Families
Protein families are groups of homologous proteins; that is, they have similarities in amino acid sequences and three-dimensional structures. Protein families usually occur because of gene duplication, where an additional copy of a gene is inserted into the genome of an organism. Mutations that change the amino acids but still allow the protein to be properly synthesized, will lead to new protein family members. If these new proteins contain similar amino acids in key locations, protein...