Small ubiquitin-related modifier 2 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''SUMO2''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
Function
This gene encodes a protein that is a member of the
SUMO
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(small ubiquitin-like modifier) protein family. It is a
ubiquitin-like protein
Ubiquitin-like proteins (UBLs) are a family of small proteins involved in post-translational modification of other proteins in a cell, usually with a regulatory function. The UBL protein family derives its name from the first member of the class ...
and functions in a manner similar to
ubiquitin
Ubiquitin is a small (8.6 kDa) regulatory protein found in most tissues of eukaryotic organisms, i.e., it is found ''ubiquitously''. It was discovered in 1975 by Gideon Goldstein and further characterized throughout the late 1970s and 1980s. Fo ...
in that it is bound to target proteins as part of a
post-translational modification
Post-translational modification (PTM) is the covalent and generally enzymatic modification of proteins following protein biosynthesis. This process occurs in the endoplasmic reticulum and the golgi apparatus. Proteins are synthesized by ribosome ...
system. However, unlike ubiquitin, which is primarily associated with targeting proteins for
proteasomal degradation
Proteasomes are protein complexes which degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. Enzymes that help such reactions are called proteases.
Proteasomes are part of a major mechanism by w ...
, SUMO2 is involved in a variety of cellular processes, such as nuclear transport, transcriptional regulation, apoptosis, and protein stability. It is not active until the last two amino acids of the
carboxy-terminus
The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is ...
have been cleaved off. Numerous
pseudogene
Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Most arise as superfluous copies of functional genes, either directly by DNA duplication or indirectly by Reverse transcriptase, reverse transcription of an mRNA trans ...
s have been reported for this gene. Alternate transcriptional
splice variant
Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be in ...
s encoding different
isoform
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene or gene family and are the result of genetic differences. While many perform the same or similar biological roles, some isof ...
s have been characterized.
Interactions
SUMO2 has been shown to
interact
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with
TRIM63
E3 ubiquitin-protein ligase TRIM63, also known as "MuRF1" (Muscle Ring-Finger Protein-1), is an enzyme that in humans is encoded by the ''TRIM63'' gene.
This gene encodes a member of the RING zinc finger protein family found in striated muscle a ...
and
CFAP298.
Clinical significance
Deep hypothermia protects the brain from ischemic injury, which is why it's employed for major cardiovascular procedures that necessitate cardiopulmonary bypass and a period of circulatory arrest. With an experiment
conducted to moderate hypothermia, small ubiquitin-like modifier (SUMO1-3) conjugation was significantly activated in the brain. The effects of hypothermia on SUMO conjugation were evaluated in this experiment
using Western blot and immunohistochemistry in animals that were either normothermic (37°C) or deep to moderate (18°C, 24°C, 30°C) hypothermic cardiopulmonary bypass. In these cells, even 30°C hypothermia was enough to significantly boost SUMO2/3-conjugated protein levels and nucleus accumulation. Deep hypothermia caused the SUMO-conjugating enzyme Ubc9 to translocate to the nucleus, implying that the increase in nuclear levels of SUMO2/3-conjugated proteins seen in hypothermic animals' brains is an active process. Deep hypothermia caused only a small increase in the amounts of SUMO2/3-conjugated proteins in primary neuronal cells. This shows that neurons in vivo have a greater capacity to activate this endogenous possibly neuroprotective mechanism when exposed to hypothermia than neurons in vitro. Identifying proteins that are SUMO2/3 conjugated during hypothermia could aid in the development of new preventive and therapeutic therapies to make neurons more resistant to a transient blood supply interruption.
References
Further reading
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