small ubiquitin-related modifier 4 (SUMO4)

Function

• ubiquitin-like protein which can be covalently attached to target Lys as a monomer
• does not seem to be involved in protein degradation
• may modulate subcellular localization
• upon oxidative stress, conjugates to various anti-oxidant enzymes, chaperones, & stress defense proteins
• may enhance protein stability & activity
• covalent attachment to its substrates requires prior activation by the E1 complex SAE1-SAE2 & linkage to the E2 enzyme UBE2I
• conjugation of transcription factors may negatively regulate their trasncriptional activity, including:
  • NFKBIA, NFKB1, TFAP2A & FOS
• conjugation of transcription factor NR3C1, positively regulates its transcriptional activity
• conjugates NFKBIA
• negatively regulates NFKB1 transcriptional activity
• in contrast to SUMO1, SUMO2 & SUMO3, seems to be insensitive to sentrin-specific proteases due to the presence of Pro-90; this may impair processing to mature form & conjugation to substrates Structure:
• belongs to the ubiquitin family, SUMO subfamily
• contains 1 ubiquitin-like domain

Expression

• expressed in adult & embryonic kidney, immune tissues, lymph nodes, spleen

Pathology

• variant Val-55 could be associated with IDDM5 (insulin-dependent diabetes mellitus 5)

More general terms

• SUMO protein (small ubiquitin-related modifier)

Additional terms

• insulin-dependent diabetes mellitus 5 (IDDM5)

Database

• OMIM: https://mirror.omim.org/entry/600320
• OMIM: https://mirror.omim.org/entry/608829
• UniProt: http://www.uniprot.org/uniprot/Q6EEV6.html