4eoz
From Proteopedia
Crystal structure of the SPOP BTB domain complexed with the Cul3 N-terminal domain
Structural highlights
Disease[CUL3_HUMAN] Pseudohypoaldosteronism type 2E. Defects in CUL3 are the cause of Pseudohypoaldosteronism type 2E (PHA2E) [MIM:614496]. An autosomal dominant disorder characterized by severe hypertension, hyperkalemia, hyperchloremia, hyperchloremic metabolic acidosis, and correction of physiologic abnormalities by thiazide diuretics.[1] Function[SPOP_HUMAN] Inhibits IPF1/PDX1 transactivation of established target promoters, such as insulin, may be by recruiting a repressor complex (By similarity). In complex with CUL3, involved in ubiquitination of BMI1, H2AFY and DAXX, and probably also in ubiquitination and proteasomal degradation of Gli2 or Gli3.[2] [3] [4] [CUL3_HUMAN] Core component of multiple cullin-RING-based BCR (BTB-CUL3-RBX1) E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. As a scaffold protein may contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. The E3 ubiquitin-protein ligase activity of the complex is dependent on the neddylation of the cullin subunit and is inhibited by the association of the deneddylated cullin subunit with TIP120A/CAND1 (By similarity). The functional specificity of the BCR complex depends on the BTB domain-containing protein as the susbstrate recognition component. BCR(SPOP) is involved in ubiquitination of BMI1/PCGF4, H2AFY and DAXX, and probably GLI2 or GLI3. BCR(KLHL9-KLHL13) controls the dynamic behavior of AURKB on mitotic chromosomes and thereby coordinates faithful mitotic progression and completion of cytokinesis. BCR(KLHL12) is involved in ER-Golgi transport by regulating the size of COPII coats, thereby playing a key role in collagen export, which is required for embryonic stem (ES) cells division: BCR(KLHL12) acts by mediating monoubiquitination of SEC31 (SEC31A or SEC31B). BCR(KLHL3) acts as a regulator of ion transport in the distal nephron; possibly by mediating ubiquitination of SLC12A3/NCC. Involved in ubiquitination of cyclin E and of cyclin D1 (in vitro) thus involved in regulation of G1/S transition.[5] [6] [7] [8] [9] [10] Publication Abstract from PubMedThe E3 ligases recruit substrate proteins for targeted ubiquitylation. Recent insights into the mechanisms of ubiquitylation demonstrate that E3 ligases can possess active regulatory properties beyond those of a simple assembly scaffold. Here, we describe the dimeric structure of the E3 ligase adaptor protein SPOP (speckle-type POZ protein) in complex with the N-terminal domain of Cul3 at 2.4 A resolution. We find that SPOP forms large oligomers that can form heteromeric species with the closely related paralog SPOPL. In combination, SPOP and SPOPL (SPOP-like) form a molecular rheostat that can fine-tune E3 ubiquitin ligase activity by affecting the oligomeric state of the E3 complex. We propose that adaptor protein self-assembly provides a graded level of regulation of the SPOP/Cul3 E3 ligase toward its multiple protein substrates. Adaptor protein self-assembly drives the control of a cullin-RING ubiquitin ligase.,Errington WJ, Khan MQ, Bueler SA, Rubinstein JL, Chakrabartty A, Prive GG Structure. 2012 Jul 3;20(7):1141-53. Epub 2012 May 24. PMID:22632832[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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