E3 ubiquitin-protein ligase that mediates ubiquitination and subsequent proteasomal degradation of target proteins. E3 ubiquitin ligases accept ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates. Mediates E3 ubiquitin ligase activity either through direct binding to substrates or by functioning as the essential RING domain subunit of larger E3 complexes. Promotes monoubiquitination of SNCA (By similarity). Triggers the ubiquitin-mediated degradation of many substrates, including proteins involved in transcription regulation (POU2AF1, PML, NCOR1), a cell surface receptor (DCC), an antiapoptotic protein (BAG1), and a protein involved in synaptic vesicle function in neurons (SYP). It is thereby involved in apoptosis, tumor suppression, cell cycle, transcription and signaling processes. Has some overlapping function with SIAH1. Triggers the ubiquitin-mediated degradation of TRAF2, whereas SIAH1 can not.
Specificity
Natural and recombinant Mouse E3 ubiquitin-protein ligase SIAH2
Homodimer. Interacts with UBE2E2. Interacts with VAV1, without mediating its ubiquitin-mediated degradation. Interacts with CACYBP/SIP. Probable component of some large E3 complex possibly composed of UBE2D1, SIAH2, CACYBP/SIP, SKP1, APC and TBL1X. Interacts with UBE2I. Interacts with PEG10, which may inhibit its activity. Interacts with EGLN2 and SNCAIP (By similarity). Interacts with PEG3.