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the state of being excluded
of or relating to alleles (同)allelomorphic

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/07/19 17:36:29」(JST)

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Allelic exclusion is a process by which only one allele of a gene is expressed while the other allele is silenced. For most genes, the individual inherits one copy of each gene from each parent.

At least two distinct selection events can lead to allelic exclusion. On one hand, one allele of the gene can be transcriptionally silent, which would result in the expression of only the second allele. On the other hand, both alleles can be transcribed, in which case posttrancriptional and posttranslational mechanisms will lead to the elimination of the protein product of one allele.

Though the mechanism by which allelic exclusion occurs is not fully understood.^[1]

Allelic exclusion in B-Lymphocytes[edit]

Allelic exclusion has been observed most often in genes for cell surface receptors and has been extensively studied in immune cells such as B lymphocytes.^[2] In B lymphocytes, successful heavy chain gene rearrangement of the genetic material from one chromosome results in the shutting down of rearrangement of genetic material from the second chromosome. If no successful rearrangement occurs, rearrangement of genetic material on the second chromosome takes place. If no successful rearrangement occurs on either chromosome, the cell dies. As a result of allelic exclusion, all the antigen receptors on an individual lymphocyte will have the same amino acid sequence in the variable domain of the heavy chain protein. As the specificity of the antigen receptor is modulated by the variable domain of the light chain encoded by one of the immunoglobulin light chain loci, the specificities of B cells containing the same heavy chain recombination event can differ according to their light chain recombination event.

Allelic exclusion in sensory neurons[edit]

A recent study showed that CpA-methylation helps for allelic exclusion in sensory neurons.^[3]

References[edit]

^ Mostoslavsky R, Alt FW, Rajewsky K (2004). "The lingering enigma of the allelic exclusion mechanism". Cell 118 (5): 539–44. doi:10.1016/j.cell.2004.08.023. PMID 15339659.
^ Chess A (1998). "Expansion of the allelic exclusion principle?". Science 279 (5359): 2067–8. doi:10.1126/science.279.5359.2067. PMID 9537917.
^ S. Lomvardas, G. Barnea, D.J. Pisapia, M. Mendelsohn, J. Kirkland and R. Axel (2006). "Interchromosomal interactions and olfactory receptor choice". Cell 126: 403–413. doi:10.1016/j.cell.2006.06.035. PMID 16873069.

UpToDate Contents

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1. T細胞受容体の遺伝学 t cell receptor genetics
2. 免疫遺伝学 immunoglobulin genetics
3. T細胞受容体シグナル伝達 t cell receptor signaling
4. BおよびTリンパ球の正常な発生 normal b and t lymphocyte development
5. 無ガンマグロブリン血症 agammaglobulinemia

English Journal

Genetic data provided by 21 autosomal STR loci from Chinese Tujia ethnic group.

Yuan GL, Shen CM, Wang HD, Liu WJ, Yang G, Yan JW, Qin HX, Xie T, Ran H, Yuan J, Liu Z, Zhu B.SourceScientific Research and Experiment Center, The Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China, yuanguolian2013@yeah.net.
Molecular biology reports.Mol Biol Rep.2012 Dec;39(12):10265-71. doi: 10.1007/s11033-012-1903-6. Epub 2012 Oct 13.
The aim of this study was to investigate allelic frequency distribution and forensic genetic parameters of autosomal short tandem repeats (STR) loci of the population samples from 107 Tujia individuals from Chinese Hubei Province. Twenty-one autosomal STR genetic markers (D9S1122, D6S474, D6S1017, D
PMID 23065199

Japanese Journal

NKT細胞クローンマウス (免疫系の形成)

若尾宏,井上貴美子,小倉惇郎
免疫 2006, 59-67, 2006
NAID 40007380295

The positional effect of Eβ on Vβ genes of TCRβ chain in the ordered rearrangement and allelic exclusion

SUZUKI Daisuke,WANG Lili,SENOO Makoto,HABU Sonoko
International immunology 17(12), 1553-1560, 2005-12-01
NAID 10016811225

日本の雑種犬におけるマイクロサテライト多型(内科学)

大石昇,前田眞理,槙村浩一 [他],澤口聡子,林屋牧男,久保拓也,加納塁,長谷川篤彦,笠原道弘
The journal of veterinary medical science 67(10), 1055-1057, 2005-10-25
北海道から沖縄までの各地より採取した類縁関係のない日本の雑種犬182頭について遺伝的多型を調べた.10個のマイクロサテライトマーカーをそれぞれ異なった常染色体より選んだ.10座位のそれぞれにつき稀なアリルをまとめた後のアリル群の分布において, ハーディ・ワインバーグ平衡が成立していた.10座位を組み合わせた平均排除率(MEC)は0.9995であり, 犬の血縁鑑定に有効であることが示された.
NAID 110003983128

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リンク元	「対立遺伝子排除」
関連記事	「exclusion」「allelic」

「対立遺伝子排除」

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英: allelic exclusion
関: 対立遺伝子

免疫に関わる細胞で見られる現象。T細胞におけるTCRやB細胞における抗体など抗原受容体をコードする「抗原受容体遺伝子」はRAG1/2という再構成に関わる組換え酵素により遺伝子再構成が起こる。ただし、この遺伝子再構成は一方の染色体(母方 or 父方)でのみ見られる。これを対立遺伝子排除と呼ぶ。これにより1つのT/B細胞が1つの抗原受容体を発現するために必要な機構である。なお、この機構にはヒストンのアセチル化が関与しており、分子レベルで解明が行われている。