D domain of b-TrCP
[FBW1A_HUMAN] Substrate recognition component of a SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins. Recognizes and binds to phosphorylated target proteins. SCF(BTRC) mediates the ubiquitination of CTNNB1 and participates in Wnt signaling. SCF(BTRC) mediates the ubiquitination of NFKBIA, NFKBIB and NFKBIE; the degradation frees the associated NFKB1 to translocate into the nucleus and to activate transcription. Ubiquitination of NFKBIA occurs at 'Lys-21' and 'Lys-22'. SCF(BTRC) mediates the ubiquitination of phosphorylated NFKB1/nuclear factor NF-kappa-B p105 subunit, ATF4, SMAD3, SMAD4, CDC25A, DLG1, FBXO5 and probably NFKB2. SCF(BTRC) mediates the ubiquitination of phosphorylated SNAI1. May be involved in ubiquitination and subsequent proteasomal degradation through a DBB1-CUL4 E3 ubiquitin-protein ligase. Required for activation of NFKB-mediated transcription by IL1B, MAP3K14, MAP3K1, IKBKB and TNF. Required for proteolytic processing of GLI3.              
Publication Abstract from PubMed
SCF ubiquitin ligases recruit substrates for degradation via F box protein adaptor subunits. WD40 repeat F box proteins, such as Cdc4 and beta-TrCP, contain a conserved dimerization motif called the D domain. Here, we report that the D domain protomers of yeast Cdc4 and human beta-TrCP form a superhelical homotypic dimer. Disruption of the D domain compromises the activity of yeast SCF(Cdc4) toward the CDK inhibitor Sic1 and other substrates. SCF(Cdc4) dimerization has little effect on the affinity for Sic1 but markedly stimulates ubiquitin conjugation. A model of the dimeric holo-SCF(Cdc4) complex based on small-angle X-ray scatter measurements reveals a suprafacial configuration, in which substrate-binding sites and E2 catalytic sites lie in the same plane with a separation of 64 A within and 102 A between each SCF monomer. This spatial variability may accommodate diverse acceptor lysine geometries in both substrates and the elongating ubiquitin chain and thereby increase catalytic efficiency.
Suprafacial orientation of the SCFCdc4 dimer accommodates multiple geometries for substrate ubiquitination.,Tang X, Orlicky S, Lin Z, Willems A, Neculai D, Ceccarelli D, Mercurio F, Shilton BH, Sicheri F, Tyers M Cell. 2007 Jun 15;129(6):1165-76. PMID:17574027
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.