InterPro domain: IPR001232

This entry includes SKP1 and SKP1-like protein, elongin-C (also known as TCEB1). SKP1 is part of the E3 ubiquitin ligase complexes. Elongin-C has dual functions, works as a component of RNA polymerase II (Pol II) transcription elongation factor and as the substrate recognition subunit of a Cullin-RING E3 ubiquitin ligase [ 1 ].

Mammlian S-phase kinase-associated protein 1 (SKP1) is an essential component of the SCF (SKP1-CUL1-F-box protein) ubiquitin ligase complex, which mediates the ubiquitination of proteins involved in cell cycle progression, signal transduction and transcription [ 2 ]. It is also part of the ubiquitin E3 ligase complex (Skp1-Pam-Fbxo45) that controls the core epithelial-to-mesenchymal transition-inducing transcription factors [ 3 ]. Budding yeast Skp1 is a kinetochore protein found in several complexes, including the SCF ubiquitin ligase complex, the CBF3 complex that binds centromeric DNA [ 4 ], and the RAVE complex that regulates assembly of the V-ATPase [ 5 ].

Elongin-C is a general transcription elongation factor that increases the RNA polymerase II transcription elongation past template-encoded arresting sites [ 6 ]. It forms a complex with SIII regulatory subunits B, which serves as an adapter protein in the proteasomal degradation of target proteins via different E3 ubiquitin ligase complexes [ 7 ]. Elongin-C forms a complex with Cul3 that polyubiquitylates monoubiquitylated RNA polymerase II to trigger its proteolysis [ 7 ].

1. Assembly of the Elongin A Ubiquitin Ligase Is Regulated by Genotoxic and Other Stresses. J. Biol. Chem. 290, 15030-41
2. Structural basis of dimerization-dependent ubiquitination by the SCF(Fbx4) ubiquitin ligase. J. Biol. Chem. 285, 13896-906
3. Atypical ubiquitin E3 ligase complex Skp1-Pam-Fbxo45 controls the core epithelial-to-mesenchymal transition-inducing transcription factors. Oncotarget 6, 979-94
4. The Saccharomyces cerevisiae kinetochore contains a cyclin-CDK complexing homologue, as identified by in vitro reconstitution. EMBO J. 15, 3611-20
5. Skp1 forms multiple protein complexes, including RAVE, a regulator of V-ATPase assembly. Nat. Cell Biol. 3, 384-91
6. Suppressors of cytokine signaling 4 and 5 regulate epidermal growth factor receptor signaling. J. Biol. Chem. 280, 7038-48
7. ELA1 and CUL3 are required along with ELC1 for RNA polymerase II polyubiquitylation and degradation in DNA-damaged yeast cells. Mol. Cell. Biol. 27, 3211-6