The application notes include recommended starting dilutions; optimal dilutions/concentrations should be determined by the end user.
Use a concentration of 1.25 µg/ml. Detects a band of approximately 34 kDa (predicted molecular weight: 31 kDa). Good results were obtained when blocked with 5% non-fat dry milk in 0.05% PBS-T.
FunctionE3 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. Triggers the ubiquitin-mediated degradation of many substrates, including proteins involved in transcription regulation (MYB, POU2AF1, PML and RBBP8), a cell surface receptor (DCC), the cell-surface receptor-type tyrosine kinase FLT3, the cytoplasmic signal transduction molecules (KLF10/TIEG1 and NUMB), an antiapoptotic protein (BAG1), a microtubule motor protein (KIF22), a protein involved in synaptic vesicle function in neurons (SYP), a structural protein (CTNNB1) and SNCAIP. Confers constitutive instability to HIPK2 through proteasomal degradation. It is thereby involved in many cellular processes such as apoptosis, tumor suppression, cell cycle, axon guidance, transcription regulation, spermatogenesis and TNF-alpha signaling. Has some overlapping function with SIAH2. Induces apoptosis in cooperation with PEG3. Upon nitric oxid (NO) generation that follows apoptotic stimulation, interacts with S-nitrosylated GAPDH, mediating the translocation of GAPDH to the nucleus. GAPDH acts as a stabilizer of SIAH1, facilitating the degradation of nuclear proteins.
Tissue specificityWidely expressed at a low level. Down-regulated in advanced hepatocellular carcinomas.
PathwayProtein modification; protein ubiquitination.
Sequence similaritiesBelongs to the SINA (Seven in absentia) family. Contains 1 RING-type zinc finger. Contains 1 SIAH-type zinc finger.
DomainThe RING-type zinc finger domain is essential for ubiquitin ligase activity. The SBD domain (substrate-binding domain) mediates the homodimerization and the interaction with substrate proteins. It is related to the TRAF family.
Post-translational modificationsPhosphorylated on Ser-19 by ATM and ATR. This phosphorylation disrupts SIAH1 interaction with HIPK2, and subsequent proteasomal degradation of HIPK2.