small ubiquitin-related modifier 3; SUMO-3; ubiquitin-like protein SMT3A; SMT3 homolog 1; SUMO-2 (SUMO3, SMT3A, SMT3H1)

^[1]^[2]^[3]^[4]

Introduction

SUMO3 would appear to be identical with sentrin-3 & ubiquitin-like protein SMT3A^[3]

ubiquitin-like protein which can be covalently attached to target Lys either as a monomer or as a Lys-linked polymer
does not seem to be involved in protein degradation
may function as an antagonist of ubiquitin in the degradation process
plays a role in a number of cellular processes such as
- nuclear transport
- DNA replication & repair
- mitosis
- signal transduction
covalent attachment to its substrates requires prior activation by the E1 complex SAE1-SAE2 & linkage to the E2 enzyme UBE2I, & can be promoted by an E3 ligase such as PIAS1-4, RANBP2 or CBX4
polymeric chains can be formed through Lys-11 cross-linking
cleavage of precursor form by SENP1, SENP2 or SENP5 is necessary for function
interacts with SAE2 & UBE2I
covalently attached to a number of proteins (putative)
targets of sumoylation by SUMO3 include:
- topoisomerase-2^[1]
- amyloid precursor protein (APP)*^[2]
  - increased sumoylation with poly(SUMO)chains is associated with diminished A4-amyloid peptide production
  - SUMO3 immunoreactivity present in human brain may be associated with inhibition of APP proteolysis

↑ ^1.0 ^1.1 Azuma Y et al, J Cell Bil 163:477, 2003 PMID: https://www.ncbi.nlm.nih.gov/pubmed/14597774
↑ ^2.0 ^2.1 ^2.2 Li Y, Wang H, Wang S, Quon D, Liu YW, Cordell B. Positive and negative regulation of APP amyloidogenesis by sumoylation. Proc Natl Acad Sci U S A. 2003 Jan 7;100(1):259-64. Epub 2002 Dec 27. Erratum in: Proc Natl Acad Sci U S A. 2003 Jul 22;100(15):9102. PMID: https://www.ncbi.nlm.nih.gov/pubmed/12506199
↑ ^3.0 ^3.1 Ye ET et al Ubiquitin-like proteins: new wines in new bottles. Gene 248:1, 2000 PMID: https://www.ncbi.nlm.nih.gov/pubmed/10806345
↑ Wikipedia; Note: SUMO protein entry http://en.wikipedia.org/wiki/SUMO_protein