Histones - waxaa ... Doorka histones in DNA ah

Nucleic acid DNA ka mid ah halyeeyada unugyada eukaryotic, isafgaradka in dhismayaasha gaar ah mahad baakadeeyey. In Cytology ay xidhan magac gaar ah - histones. Waa peptide ah in bandhigayaa guryaha kiimikada aasaasiga ah. Waxa ay qaab-dhismeedka iyo hawlaha sameeyaa gacanta, waxaa ka wada xaajoon doona in this article.

DNA waxaa lagu qabanqaabiyaa xuduntii

Si aad u "tuujin" silsilad polynucleotide dheer DNA ee microspace bu'da unugga dhex jira hanti "gariiradda" - borotiin, histones. Waxay yihiin dun double-ku xayiran la duubo deoxyribonucleic acid. Qaab dhismeedka Tani, oo ku yaalla karyoplasm waxaa lagu magacaabaa nucleosome ah. waxbarashada lagmamaarmaanna shaaca ka qaaday protein histone in abaabulay dhowr hab doorinta: H1 histone / H5, H2A, H2B, H3, H4. peptide hore ee liiska waxa loo yaqaan linker ah, ee sac oo kale. borotiinada histone Kuwani sameeyaan nucleosome.

Features of qaab-dhismeedka peptides nucleosome

Falanqaynta Chemical aasaasay xaqiiqda ah ee content xad-dhaaf ah ee u taagoo histone muhiimka ah ee acids amino sida lysine iyo arginine. Ka hore waa lagama maarmaan ah iyo kuwa kale oo qayb ahaan laysku beddelid karo iyo waxa ay joogtaa shiidaa peptides oo dhan. borotiinada Histone uruursado lacag fiican xad-dhaaf ah oo ku saabsan harta amino acid. Waxay uga takhalusi ku eedeeyay xun ee wadarta PO ₄ ^3- anions, waxaa ka mid ahaa in DNA ah. Muuqaal kale oo ka mid ah qaab-dhismeedka borotiinada, kuwaas oo been in xaqiiqda ah in ay tahay ku dhowaad isku mid ah in noolaha ka tirsan boqortooyada dhirta, xayawaanka iyo fangaska.

Tan iyo histones - borotiinada waa xudunta, iyagu waa ay sabab u tahay qaab-dhismeedka, waxay ka qaybqaadan karaan geeddi socodka ka dhacda karyoplasm. Tusaale ahaan, waxa ugu muhiimsan in peptide qoraal H1 habka - protein histone nucleosomes xafidaada waa qayb ka mid ah chromatin in hagaagsan, core is haysta. Sidoo kale, haddii ay dhacdo of loci dhaawac DNA, si loo yaqaan taagoo kala duwanaansho peptide muhiimka ah ay ku lug leeyihiin dayactir ah ee qaybo ka mid ah kuwan.

peptide core

Waxay qeexaya qaab-dhismeedka nucleosome ah, taas oo ka kooban afar nooc oo u taagoo yeedhay H2A, H2B iyo H3 iyo H4. nucleosomes waa labo ka mid ah nooc kasta oo Britain, qaab-dhismeedka noocan oo kale ah waxaa loo yaqaan octamer. Britain ee borotiinada core deoxyribonucleic iyo qaab u dhaxeeya hydrophobic, hydrogen iyo dhaaraheedii covalent. Borotiin, histones yihiin muhimka ah ee nucleosome ah. Waxa kale oo ay ku jiraan qaabaysnayn NC-dabo. meelahakan ka kooban 15-30 harta amino acid iyo ka qayb qaataan geeddi socodka ah epigenetic in la xakameeyo hadal hiddo. histones Core nucleosomes qayb dhexe leeyihiin miisaanka yar kelli, meelaha ay, ka duwan Islets qaybood oo dabada ku jira monomers hydrophobic valine protein, proline, Lezina methionine.

cilmi Recent berrinkii Kiimikada noole ayaa keentay in la xiqiijiyay of code histone ah. Marka la barbardhigo code hidaha waa universal dhammaan noocyada nolosha gacanta on Earth, code histone waa variable. Ereygan waxaa loola jeedaa bedelayaan qaybood oo dabada ee peptides ka dhalanaya ka reaction acetylation, methylation, phosphorylation ah. Oo intaas oo dhammu hababka kiimikada dhacaan joogitaanka kaxeynayo multienzyme. Sababo la xidhiidha geedi socodka lagmamaarmaanna u ah sida, ka bedelayaan histones asaasiga ah, iyo sixitaanka qaadataa hadal meel ka mid ah hiddo-in la xakameeyo reactions intranuclear ku lug leh DNA: dayactir, qoraal, taranka. Xaggiisa sarkhaansan oo ka mid ah chromatin code histone isbedel Oo Qaliin hagaajay, ie beddelo ay Baakadaha in nucleosome ah (u Daabacaa ama, on lid ku ah, ka fuqdo).

protein linker

Histone H1 waa in chromatin, ku xiran yahay in qaybta sare ee nucleosome iyo xajisto ku dul supercoil deoxyribonucleic acid. Its u qardarin dhacdaa tetramer meesha ka kooban laba taagoo peptide H3 iyo H4 laba taagoo. The wakiillo ka socda fasalka iyo fasalka ka mid ah shimbiraha xamaarato ee unugyada dhiigga cas halkii protein linker H1 histone helay H5 kale.

peptide H1 ka kooban HMJB-domain - Qayb dhismaha, iyadoo ku harta acid qiyaastii 80 amino. Waxa uu ficil ahaan waa isku mid ee noolaha ugu, oo ay ku jiraan dhirta, xayawaanka iyo bini'aadanka. domain Tani ma hoos gasho baddalista oo waa muxaafid. Peptide N1 waxay leedahay laba nooc oo gaadmada ah da'ayeen: globule dumay oo biloowday - foomka jaamacadeed. Arintaan waxay dhacdaa marka isgaarsiinta guuldareysto gobolka C-terminal ee histone si domains DNA-dhaba ah. peptide linker waxaa si firfircoon uga qayb koobiyeynta macluumaadka ka hiddo in Britain mRNA, a geedi socodka DNA is-laabma, iyo sidoo kale in dayactirka ah ee waxyeello ay loci. Tani waa doorka noolaha ee histones in DNA ah.

Sida borotiinada sameeyaan octamer

Si ka duwan peptide H1, noocyada kale ee histones yeedhay lo'da, lagu gartaa ductility ku filan si ay u sameeyaan qaab kala duwanaansho ah. Tusaale ahaan, H2A ayaa tirada ugu badan ee hab doorinta: H2AZH2AX MACROH2A. Waxay ku kala duwan ka soo midba midka kale:

• C-terminal xigxiga amino acid.
• Location ee hiddawadayaasha ah.

Tusaale ahaan, kala duwanaansho histone H2ABbd isku xidhan la chromatin kaas oo qoraal DNA dhacdaa. MACROH2A peptide waa in koromosoomyada interphase. waxbarashada Cytological waxaa la ogaaday in foomamka duwanaansho H4 histone loo aqoonsaday, laakiin waxa ay abuuri karaan tiro badan oo ah bonds covalent la borotiinada kale ay leeyihiin ee nucleosomes octamer. Sayidka, saynisyahano aaminsan yihiin in histones ah - oo ah koox gaar ah oo ka mid ah borotiinka in ficil ahaan waa qayb ka mid ah chromatin ee dhammaan foomamka gacanta nolosha.

Sidee ku kaydsan wax warbixin ah oo ku saabsan histones ee hiddawadayaasha ah

Waxa lagu murmi karaa in ay lo'da, iyo kala duwanaansho histone linker ku encoded in kooxahaasi hiddo muujiyay in wajiga dardaro oo ka mid ah wareegga nolosha gacanta ee. Tusaale ahaan, koox sifooyin kala dhaxlo aadanaha yeedhay HIST1 waxay ka kooban tahay 35 hiddo ku yaal labada ciyaaryahan koromosoom degaaankaaga lixaad. HIST2 kooxdu ka kooban lix hiddo-habaynteeda histones, iyo meesha koromosoomyada ah labo ka mid ah kuwii hore ka. Waxa kale oo ku jira HIST3 kaledii ah, oo ka kooban saddexda hiddo. In labada ciyaaryahan iyo tobnaad waa mid ka mid hiddo-habaynteeda H4 histone ah. Waxa xiiso leh, hiddo-protein core leeyihiin introns, iyo hiddo-ee histones duwanaansho, on lid ku ah, iyaga oo ku jira waxaa lagu kala firdheen hiddawadayaasha ah.

Si Loo soo kobo, waxaan ogaannay in histones ah - borotiinada ku lug leh oo yeynan ku qaybood ee DNA ee xuduntii, laakiin sidoo kale in habka of regulation, dayactirka iyo qoraal ka dhici waxa ku jira.