※ 引述《loneloneago (你是最好的 知道嗎)》之銘言：
: 請問一下 snRNPs在DNA變成蛋白質的過程中 扮演什麼角色??
: 我只知道在splicing的時候 snRNPs會參與 可是不太清楚它的功能
: 麻煩幫在下解答 下禮拜就要期中考了〒△〒
給你二個流程圖
http://mips.gsf.de/proj/yeast/images/intron//step_RNP.gif
http://mips.gsf.de/proj/yeast/images/intron//penta_snRNP.gif
說明文字如下
The spliceosomal machinery (重點在最後二段) S. cerevisiae是一種酵母菌....
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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