【正文】
100bp) Chromatin protein Histone protein Sructure protein Nohistone protein : sequence specific DNA binding protein Nucleosome protein H2B,H2A,H3,H4, conservative H1,link function Chromatin protein A Histone ? 富含堿性氨基酸 ? H2A, H2B, H3, and H4, 沒有種屬特異性 ,相對保守 ? H1, H1是多樣性 , 具有屬 (genus)和組織特異性 。 ? 結(jié)構(gòu):高度保守,尤其是 H4。 ? H1是多樣性,具有屬 (genus)和組織特異性。 ◆ 200 bp DNA and four type histone; ◆ H2A、 H2B、 H H4 ,every type two copy form octamoric core , is key structure of Nucleosome ◆ 146bp DNA surround octamoric core circle ,H1 play stablization function in chromatin formation ◆ Neighborhood nucleosome connect with linker DNA link (about ~ 100bp) Chromatin assemble Multiple coiling model 通過核小體, DNA長度壓縮 7倍,形成 11nm的纖維。 ? 對于更高級染色體包裝方式,至今尚不明確。 Scaqffold radial loopsructure model Synthetical model Chromatin type ? Euchromatin: open structure – active genes ? Heterochromatin: highly packaged structure – inactive genes ◆ 常染色質(zhì) (euchromatin) ◆ 異染色質(zhì) (heterochromatin) ● 結(jié)構(gòu)性異染色質(zhì) (active chromatin) ● 兼性異染色質(zhì) (inactive chromatin) ? Chracterristic of active chromatin ? Nucleosome and gene regulation Chromatin and regulation 轉(zhuǎn)錄 的摸板是疏松的染色 質(zhì) 而不是裸露 DNA 形成疏松的染色質(zhì) 形成活性染色質(zhì) nuclease supersensitive site A Chracterristic of active chromatin B Nucleosome and gene regulation Core Histone acetyl H1P HMG protein modification ? Locus control region LCR ? Insulator C Chromatin domain Chapter Chromosome Chromosome structure NOR ◆ 著絲粒 (Centromere) ● 主縊痕 (Primary constriction) ◆ 次縊痕 (Secondary constriction) ◆ 動粒 (kiochore) ◆ 核仁組織區(qū) (NOR) ◆ 隨體 (Satellite) ◆ 端粒 (Telomere) Centromere and kiochore centromere Kiochore domain Inner plate Middle space Outer plate fibrouscorona Central domain Pairing domain