SP-RING finger found in zinc finger MIZ domain-containing protein 1 (Zmiz1) and similar proteins
Zmiz1, also known as PIAS-like protein Zimp10 (zinc finger-containing, Miz1, PIAS-like protein on chromosome 10) or retinoic acid-induced protein 17, is a novel PIAS-like protein that was initially identified as an androgen receptor (AR) interacting protein and functions as a transcriptional co-activator. It co-localizes with AR and small ubiquitin-like modifier SUMO-1, forms a protein complex at replication foci in the nucleus, and augments AR-mediated transcription. It also functions as a transcriptional co-activator of the p53 tumor suppressor that plays a critical role in cell cycle progression, DNA repair, and apoptosis. Moreover, Zmiz1 dysfunction may be associated with multiple autoimmune diseases and it has been implicated in the development, function, and survival of melanocytes. Zmiz1 also interacts with Smad3/4 proteins and augments Smad-mediated transcription, suggesting it is important in the regulation of the transforming growth factor beta (TGF-beta)/Smad signaling pathway and may have an inhibitory effect on the immune system. Zmiz1 is overexpressed in a significant percentage of human cutaneous squamous cell carcinoma (SCC), breast, ovarian, and colon cancers, suggesting it may play a broader role in epithelial cancers. It functionally interacts with NOTCH1 to promote C-MYC transcription and activity, and thus is involved in a variety of C-MYC-driven cancers. Zmiz1 contains a PAT domain, a highly conserved Siz/PIAS (protein inhibitor of activated signal transducer and activator of transcription) RING (SP-RING) finger, also known as msx-interacting zinc finger (Miz domain), and a putative nuclear localization sequence (NLS), as well as a strong intrinsic transactivation domain within the C-terminus. The SP-RING finger is a variant of RING finger, which lacks the second, fifth, and sixth zinc-binding residues of the consensus C3H2C3-/C3HC4-type RING fingers. It binds a single Zn ion, instead of two ions bound by typical RING fingers.
Comment:based on the structures of human Sumo ligases Pias2 and Pias3 with bound Zn2+ ion through their SP-RING fingers
Comment:The SP-RING finger is a variant of RING finger; it binds a single Zn ion and lacks the second, fifth, and sixth zinc-binding residues of the consensus C3H2C3-/C3HC4-type RING fingers.
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