※ 引述《loneloneago (你是最好的 知道吗)》之铭言： : 请问一下 snRNPs在DNA变成蛋白质的过程中 扮演什麽角色?? : 我只知道在splicing的时候 snRNPs会参与 可是不太清楚它的功能 : 麻烦帮在下解答 下礼拜就要期中考了〒△〒 给你二个流程图 http://mips.gsf.de/proj/yeast/images/intron//step_RNP.gif http://mips.gsf.de/proj/yeast/images/intron//penta_snRNP.gif 说明文字如下 The spliceosomal machinery (重点在最後二段) S. cerevisiae是一种酵母菌.... Unlike Group I and Group II introns, pre-mRNA introns are not able to self-splice without the assistance of trans- acting RNA or protein factors. Splicing of precursor messenger RNA takes place in the spliceosome, a large (~40S) RNA/protein macromolecular machine assembles de novo at each round of splicing. The spliceosomal machinery complex is formed from five ribonucleo- protein subunits, termed uridine-rich small nuclear nucleoproteins (snRNPs), transiently associated to more than 760 non-snRNPs splicing factors (RNA helicases, SR splicing factors, etc...). Each snRNP particle consists of a phylogenetically conserved small nuclear RNA molecule (abbreviated snRNA) complexed with a set of seven Sm or Sm-like proteins (Lsm), and several snRNP-specific proteins. Thus, the S. cerevisiae U1 snRNP contains ten specific proteins as opposed to three in mammals, the U2 snRNP eleven associated proteins, and the U4/U6.U5 snRNP thirteen protein s. Surprisingly, the yeast DEAD-box helicase-like protein Prp28 is stably as sociated with the U5 snRNP, yet is absent from the purified U4/U6 x U5 snRNP . This latter is composed of the two U5-specific proteins and the 7 proteins of the canonical Sm core. The U6 snRNP is composed of the U6 snRNA, Prp24, and the 7 Lsm proteins. The major spliceosomal snRNPs U1, U2, U4, U5 and U6 are responsible for spli- cing the vast majority of pre-mRNAs (so-called U2 introns). A group of less abundant snRNPs, U11, U12, U4atac, and U6atac, together with U5,are subunits of the so-called minor spliceosome that splices, only in metazoan (plant, insects and vertebrates), a rare class of pre-mRNA introns, denoted U12-type. --

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