
Overview:
SMAD4 is a member of the SMAD family and mediates signaling by the transforming growth factor-beta (TGFB) superfamily and related ligands (1). TGFB stimulation leads to phosphorylation and activation of SMAD1, SMAD2 and SMAD3, which form complexes with SMAD4 that accumulate in the nucleus and regulate transcription of target genes. SMAD signaling is negatively regulated by inhibitory SMADs and ubiquitin-mediated processes and proteasomal degradation of SMADs depend on the direct interaction of specific E3 ligases with SMADs. SMAD4 is targeted for degradation by multiple ubiquitin ligases that can simultaneously act on R-SMADs and signaling receptors. Such mechanisms of down-regulation of TGFB signaling via degradation of SMADs may be critical for proper physiological response to this pathway (2).
Gene Aliases:
JIP, DPC4, MADH4
Genbank Number:
NM_005359
References:
1. Heldin, C.H. et al: TGF-beta signalling from cell membrane to nucleus through SMAD proteins". Nature, 1997, 390 (6659): 465-71.2. Attisano, L. et al: Mads and Smads in TGF beta signalling". Curr. Opin. Cell Biol. 1998; 10 (2): 188-94.
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植物材料 用最精确的方法,称取不超过100mg的植物材料,置于处理过的研钵,加入液氮进行研磨 将研磨得到的粉末,快速转移至无RNase,并经过液氮冷却的2mL离心管(自备),
但是,这样做的前提的,RNA提得要好,浓度要高,这样免得RNA降解到不能用了。因为在有二价阳离子的(DNAseI buffer含有)情况下,RNA在60度以上时必然发生非酶促降解。
想搞清一个问题,如何区别是因为small RNA 引起的调控呢?还是tRNA引起的调控,有没有有效的分离这两种RNA的办法呢?
样品处理:
a. 植物组织:取新鲜或-70℃冻存100mg组织在液氮中研磨,把粉末加入到1ml裂解液中混匀。
b. 动物组织:取新鲜或-70℃冻存100mg组织加1ml裂解液,用组织研磨杵或匀浆器匀浆处理。
c. 贴壁细胞:直接在培养板中加入裂解液裂解细胞,每106细胞加1ml 裂解液。用取样器吹打混匀。

