4bbn | pdb_00004bbn
NEDD4 HECT-Ub:Ub complex
Structural highlights
Function[NEDD4_HUMAN] E3 ubiquitin-protein ligase which accepts ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates. Involved in the pathway leading to the degradation of VEGFR-2/KDFR, independently of its ubiquitin-ligase activity. Monoubiquitinates IGF1R at multiple sites, thus leading to receptor internalization and degradation in lysosomes. Ubiquitinates FGFR1, leading to receptor internalization and degradation in lysosomes. According to PubMed:18562292 the direct link between NEDD4 and PTEN regulation through polyubiquitination described in PubMed:17218260 is questionable. Involved in ubiquitination of ERBB4 intracellular domain E4ICD. Involved in the budding of many viruses. Part of a signaling complex composed of NEDD4, RAP2A and TNIK which regulates neuronal dendrite extension and arborization during development. Ubiquitinates TNK2 and regulates EGF-induced degradation of EGFR and TNF2.[1] [2] [3] [4] [5] [UBB_BOVIN] Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, DNA-damage responses as well as in signaling processes leading to activation of the transcription factor NF-kappa-B. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling (By similarity). Publication Abstract from PubMedHomologous to E6-AP C terminus (HECT) E3 ligases recognize and directly catalyze ligation of ubiquitin (Ub) to their substrates. Molecular details of this process remain unknown. We report the first structure, to our knowledge, of a Ub-loaded E3, the human neural precursor cell-expressed developmentally downregulated protein 4 (Nedd4). The HECTNedd4~Ub transitory intermediate provides a structural basis for the proposed sequential addition mechanism. The donor Ub, transferred from the E2, is bound to the Nedd4 C lobe with its C-terminal tail locked in an extended conformation, primed for catalysis. We provide evidence that the Nedd4-family members are Lys63-specific enzymes whose catalysis is mediated by an essential C-terminal acidic residue. Structure of a ubiquitin-loaded HECT ligase reveals the molecular basis for catalytic priming.,Maspero E, Valentini E, Mari S, Cecatiello V, Soffientini P, Pasqualato S, Polo S Nat Struct Mol Biol. 2013 May 5. doi: 10.1038/nsmb.2566. PMID:23644597[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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