PROSITE documentation PDOC51466
PINIT domain profile


The Siz/PIAS RING family of SUMO E3 ligases structure reveals a modular architecture that includes an N-terminal PINIT domain, a central SP-RING domain (see <PDOC51044>), and a unique C-terminal domain (SP-CTD). The N-terminal PINIT domain is formed by two antiparallel β sheets; one includes β1, β2, β4, and β9, and the other includes β3, β5, and β8 (see <PDB:3I2D; A>). The β sheets are connected by protruding loops (L1, L2, and L3) that join strands β2-3, β4-5, and β8-9 at one end of the molecule, while β3-4 and β5-8 are connected by α helix α1 and a loop, respectively, on the opposite surface [1].

Most E3 ligases achieve substrate specificity by recruiting the E2~Ub/Ubl thioester and substrate into a complex to promote conjugation. The PINIT domain serves as a scaffold to coordinate PCNA to promote SUMO conjugation to both consensus and nonconsensus lysine side chains [1].

The profile we developed covers the entire PINIT domain.

Last update:

October 2009 / First entry.


Technical section

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

PINIT, PS51466; PINIT domain profile  (MATRIX)


1AuthorsYunus 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

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