发信人: clonist (chill out), 信区: Biology
标 题: Re: 问题？3'UTR
发信站: The unknown SPACE (Sun Nov 10 18:30:56 2002), 站内信件

since i'm in this field i think sth should be clarified. so far
the only functional miRNAs has been found in worms and plant
but not in mammlian cells although miRNAs are detected in mammalian
cells. no targets have been found yet. also in worms miRNA (actually
let-7 and lin-4) is not perfectly complenentary to its target
seq at 3'UTR. some bulges exist withink base paring region. this
posts most difficult part to identify potential miRNA target
seq since it's not perfectly match. also miRNA is different from
RNA interference (RNAi) in that miRNA doesn't destroy mRNA but
inhibit its translation while siRNA leads RISC to cut target
seq. it's been hypothesized that miRNA and siRNA do share some
common factors even common pathways as recent Science paper from
Zamore lab showed let-7 in hela cell extract can cut artificial
complementary target. but nobody knows what's the difference
between both pathways and how to distinguish it yet.

【 在 Marble (小石头哥哥) 的大作中提到: 】
: it is hypothesized that the recently found microRNAs (miRNAs)
: interact with genes whose 3'-UTR is complementary to the seq.
: of miRNAs and thus translationally repress the message. it was
: first found in C. elegans as temporal RNAs since their expressions
: are developmentally regulated, then several labs found there
: are actually similar RNAs (very small, about 21nt) that exist
: in mammalian and plants. thus, it further highlights the
: important of RNA interference at a physiological aspect in the
: eukaryotes. very important and interesting finding, and it
: suggests that we have for a long time underestimate the function
: of RNAs.
: 【 在 clonist (chill out) 的大作中提到: 】
: : 3' UTR has lots of important roles in gene regulation including
: : mRNA 3' formation, processing, maturation, stablization, error
: : proof scan, export and translational control. but usually 3'UTR
: : is exchangable for most genes. therefore lot of commercial vectors
: : use very strong 3'UTR to boost expression


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