Overview:
IκBα is an inhibitor of the NFκB complex and inactivates the NFκB by trapping it in the cytoplasm (1). Phosphorylation of serine residues on the IκB protein by IκB kinases (IKKs) marks it for destruction via the ubiquitination pathway, thereby allowing the activation of the NFκB complex. Synthetic glucocorticoid such as dexamethasone display anti-inflammatory effects by inducing the increased synthesis of the IκB protein thereby inhibiting the activity of the NFκB complex. Overexpressionof the IκBα gene in fibroblasts leads to inhibition of production of IL-6, TNF receptor, MMP-1, MMP-3 and MMP-13 (2).
Gene Aliases:
NFKBIA, MAD-3, NFKBI
Genbank Number:
NM_020529
References:
1.Auphan, N. Et al: Immunosuppression by glucocorticoids: inhibition of NF-kappa-B activity through induction of I-kappa-B synthesis. Science 270: 286-290, 1995. 2.Bondeson, J. Et al: Adenoviral gene transfer of the endogenous inhibitor IkappaBalpha into human osteoarthritis synovial fibroblasts demonstrates that several matrix metalloproteinases and aggrecanases are nuclear factor-kappaB-dependent. J Rheumatol. 2007 Mar;34(3):523-33.
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非常急！
蛋白质在水溶液中的溶解度是由蛋白质周围亲水基团与水形成水化膜的程度，以及蛋白质分子带有电荷的情况决定的。当用中性盐加入蛋白质溶液，中性盐对水分子的亲和力大于蛋白质，于是蛋白质分子周围的水化膜层减弱乃至消失。同时，中性盐加入蛋白质溶液后，由于离子强度发生改变，蛋白质表面电荷大量被中和，更加导致蛋白溶解度降低，使蛋白质分子之间聚集而沉淀。一般33%硫酸铵为沉淀Ig-G的最适饱和度
有机溶剂沉淀，极性有机溶剂降低介点常数使蛋白质凝集沉淀。eg.甲醇、乙醇、丙酮。
磺基水杨酸也可以沉淀蛋白质，但要加酸调节ph，使之低于血清蛋白的pi，使蛋白质带正电荷，与水杨酸酸根结合生成不溶盐而沉淀。
血清蛋白质均带负电荷，但各种蛋白质带负电荷的程度有所差异，以白蛋白为最多。而血清白蛋白等电点为4.7－4.9。所以把ph调到4.7以下就可以了。
