Small Ubiquitin-related Modifier or SUMO proteins are a family of small proteins that are covalently attached to and detached from other proteins in cells to modify their function. SUMOylation is a post-translational modification involved in various cellular processes, such as nuclear-cytosolic transport, transcriptional regulation, apoptosis, protein stability, response to stress, and progression through the cell cycle. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Covalently bonded hydrogen and carbon in a molecule of methane. ... Cells in culture, stained for keratin (red) and DNA (green). ... Posttranslational modification means the chemical modification of a protein after its translation. ... In cell biology, the nucleus (from Latin nucleus or nuculeus, kernel) is found in all eukaryotic cells and contains the nuclear genes which form most of the cells genetic material. ... ÃThe cytosol (as opposed fatty cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. ... Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. Or, in other words, the transfer of genetic information from DNA into RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately... A cell undergoing apoptosis. ... The cell cycle, or cell-division cycle (CDC), is the cycle of events in a eukaryotic cell from one cell division to the next. ...

SUMO proteins are similar to ubiquitin. In contrast to ubiquitin, SUMO is not used to tag proteins for degradation. The protein is not active until the last four amino acids of the C-terminus have been cleaved off. Ubiquitin is a small regulatory protein that is ubiquitous in eukaryotes. ... Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion. ...

SUMO family members often have dissimilar names; the SUMO1 homologue in yeast, for example, is called SMT3 (suppressor of mif two 3). Several pseudogenes have been reported for this gene. Yeasts are single-celled (unicellular) fungi, a few species of which are commonly used to leaven bread, ferment alcoholic beverages, and even drive experimental fuel cells. ... A pseudogene is a nucleotide sequence that is part of the genome of an organism that appears to code for a gene product (typically a protein) but does not (or no longer does so). ...

Structure schematic of human SUMO1 protein made with iMol and based on PDB file 1A5R, an NMR structure; the backbone of the protein is represented as a ribbon, highlighting secondary structure; N-terminus in blue, C-terminus in red

The same structure represented with atoms represented as spheres to show the shape of the protein; human SUMO1, PDB file 1A5R

Function

SUMO modification of proteins has many functions. Among the most frequent and best studied are protein stability, nuclear-cytosolic transport, transcriptional regulation. Unlike ubiquitin modification which targets proteins for degradation, SUMOylation increases a protein's lifetime. It can also change a protein's location in the cell. For example, the Sumo modification of hNinein leads to its movement from the centrosome to the nucleus [1]. In most cases Sumo attachment to transcriptional regulators correlates with inhibition of transcription [2]. There are many more proposed functions. Refer to the GeneRIFs of the Sumo proteins, e.g. human SUMO1 [3], to find out more. In cell biology, the nucleus (from Latin nucleus or nuculeus, kernel) is found in all eukaryotic cells and contains the nuclear genes which form most of the cells genetic material. ... ÃThe cytosol (as opposed fatty cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. ... Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. Or, in other words, the transfer of genetic information from DNA into RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately... Ubiquitin is a small regulatory protein that is ubiquitous in eukaryotes. ... The centrosome is the main microtubule organizing center (MTOC) of the cell as well as a regulator of cell-cycle progression. ... Nucleus usually refers to the center of something, but can mean: In science: Atomic nucleus, the collection of protons and neutrons in the center of an atom that carries the bulk of the atoms mass and positive charge Cell nucleus, the membrane-bound subcellular organelle found in eukaryotes, visible...

Structure

Sumo proteins are small proteins; most are around 100 amino acids in length and 12 kDa in mass. The exact length and mass varies between Sumo family members and depends on which organism the protein comes from. For example, human SUMO1, also shown in the figures, is 101 residues long and has a mass of 11.6 kDa. Its homologues in rat and mice are also 101 residues long, while the presumed relative in C. elegans has only 91 amino acids. In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Possible meanings: Kachin Defense Army Kentucky Distillers Association Kongsberg Defence & Aerospace This page expands a three-character combination which might be any or all of: an abbreviation, an acronym, an initialism, a word in English, or a word in another language. ... Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... In biology and ecology, an organism (in Greek organon = instrument) is a living complex adaptive system of organs that influence each other in such a way that they function as a more or less stable whole. ... In biology, two or more structures are said to be homologous if they are alike because of shared ancestry. ... Binomial name Caenorhabditis elegans Wild-type C. elegans hermaphrodite stained to highlight the nuclei of all cells Caenorhabditis elegans () is a free-living nematode (a roundworm), about 1 mm in length, which lives in a temperate soil environment. ...

The structure of human SUMO1 is depicted on the right. It shows SUMO1 as a globular protein with both ends of the amino acid chain (shown in red and blue) sticking out of the protein's centre. The spherical core consists of an alpha helix and a beta sheet. The diagrams shown are based on an NMR analysis of the protein in solution. A diagram of the alpha helix structure of amino acids In proteins, the α helix is a major structural motif in secondary structure. ... Diagram of Î’-Pleated sheet and bond structure of protein The β sheet (also β-pleated sheet) is a commonly occurring form of regular secondary structure in proteins, first proposed by Linus Pauling and Robert Corey in 1951. ... NMR may refer to: Nuclear magnetic resonance, a phenomenon involving the interaction of atomic nuclei and external magnetic fields Nielsen Media Research, a U.S. company which measures TV, radio and newspaper audiences This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the...

External links

• SUMO1 homology group from HomoloGene
• human SUMO proteins on ExPASy: SUMO1 SUMO2 SUMO3 SUMO4
• UniProt entry for rat Sumo1
• SUMO conjugation sequence in the SCAN protein family (PubMed Bookshelf)

review on the topic

• connection between ubiquitin & SUMO modification, 2005
• effect of SUMO on transcription, 2005
• possible link between Sumo & diabetes, 2005

examples of research groups working on SUMO:

• Mary Beth Mudgett's lab (plants & bacterial infection)
• Peter O'Hare's lab (Herpes virus)
• Mary Dasso's section on cell cylce control
• Mary Ann Handel's lab (meiosis, spermatogenesis)
• Nam-Hai Chua's lab (plants, protein modification)
• Frauke Melchior's personal page
• Stefan Jentsch's lab
• Bones lab (plant immunology) has a summary page on sumoylation