PROSITE documentation PDOC51044
Zinc finger SP-RING-type profile


SIZ1, SIZ2, and PIAS (protein inhibitor of activated STAT) proteins form a conserved family defined by an unusual RING-related domain, the Siz/PIAS RING finger (SP-RING) [1]. While RING fingers coordinate two Zn2+ ions, with a cross-brace architecture, the SP-RING finger contains only one Zn2+ ion in site B, which is coordinated in a tetrahedral configuration (see <PDB:3I2D>). Three of the four amino acid side chains that coordinate the Zn2+ ion at site A in RING proteins are lacking in Siz/PIAS proteins [2]. Like classical RING fingers SP-RINGs function as an E3 enzyme but specific for sumoylation (see <PDOC00449> for more details on the ubiquitination pathway). The SP-RING zinc finger has the capacity to interact with Ubc9 (the SUMO specific E2 enzyme) and the substrate and thus can increase the rate of substrate sumoylation [3,4].

Some proteins known to contain an SP-RING zinc finger are listed below:

  • Mammalian PIAS proteins (PIAS 1,3,x and y). They bind to STAT transcription factors and prevent STAT-activated transcription. The mouse PIAS3 protein has also been called Msx-interacting-zinc finger protein (Miz1) [5].
  • Drosophila Su(var)2-10. It is required for proper chromosome structure and chromosome inheritance [6].
  • Yeast SIZ1 and SIZ2. They are required for SUMO attachment to the cytoskeletal septin proteins.
  • Pli1, the unique fission yeast member of the SP-RING family. It is involved in centromeric function.

The profile we developed covers the whole SP-RING-type zinc finger.


The SP-RING-type zinc finger is also known as the MIZ-type zinc finger [5].

Last update:

March 2021 / Profile revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

ZF_SP_RING, PS51044; Zinc finger SP-RING-type profile  (MATRIX)


1AuthorsHochstrasser M.
TitleSP-RING for SUMO: new functions bloom for a ubiquitin-like protein.
SourceCell 107:5-8(2001).
PubMed ID11595179

2AuthorsYunus A.A. Lima C.D.
TitleStructure of the Siz/PIAS SUMO E3 ligase Siz1 and determinants required for SUMO modification of PCNA.
SourceMol. Cell 35:669-682(2009).
PubMed ID19748360

3AuthorsJohnson E.S. Gupta A.A.
TitleAn E3-like factor that promotes SUMO conjugation to the yeast septins.
SourceCell 106:735-744(2001).
PubMed ID11572779

4AuthorsSeeler J.S. Dejean A.
TitleNuclear and unclear functions of SUMO.
SourceNat. Rev. Mol. Cell Biol. 4:690-699(2003).
PubMed ID14506472

5AuthorsWu L. Wu H. Ma L. Sangiorgi F. Wu N. Bell J.R. Lyons G.E. Maxson R.
TitleMiz1, a novel zinc finger transcription factor that interacts with Msx2 and enhances its affinity for DNA.
SourceMech. Dev. 65:3-17(1997).
PubMed ID9256341

6AuthorsHari K.L. Cook K.R. Karpen G.H.
TitleThe Drosophila Su(var)2-10 locus regulates chromosome structure and function and encodes a member of the PIAS protein family.
SourceGenes Dev. 15:1334-1348(2001).
PubMed ID11390354

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