IKK_a: An Update

Abstract: IkB kinase or IKK complex， which is one important component of NF-kB signaling pathway， consists of three subunit: IKK_a， IKK_b as catalytic subunits and IKK_g as modulator subunit. NF-kB proteins are dimmers， comprising a DNA-binding subunit (such as p50 or p52) and a transcription-activating subunit (such as p65 or RelB). In cells that have not received appropriate external cues， NF-kB are kept inactive either by a member of the IkB family in the classical pathway， or by an inactive precursor (such as p100) in the alternative pathway. When stimulated by proteins such as TNF-a or lymphotoxin b， the IKK complex is activated. It phosphorylates IkB and /or p100， leading to degradation of IkB and the processing of p100 into a smaller， p52 form. NF-kB is then free to move into the nucleus and activates target genes. Recent studies reveals that IKK_a can itself move into the nucleus where it regulates the expression of NF-kB-responsive genes rapidly via phosphorylating histone 3 on serine 10. It is the first discovery that IKK_a being the upstream component of signaling pathway moves into the nucleus directly and regulates the expression of target genes， which open up a new avenue of research into the NF-kB signaling pathway.
    

CSTR: 32200.14.cjcb.2006.03.0007