The small ubiquitin-related modifier (SUMO) proteins, which include SUMO-1, SUMO-2, SUMO-3 and SUMO-4, belong to the ubiquitin-like protein family. Like ubiquitin, the SUMO proteins are synthesized as precursor proteins that undergo processing before conjugation to target proteins. Ubiquitin and SUMO proteins utilize the E1, E2 and E3 cascade enzymes for conjugation. However, SUMO and ubiquitin differ with respect to targeting. Ubiquitination predominantly targets proteins for degradation, whereas sumoylation targets proteins for a variety of cellular processing, including nuclear transport, transcriptional regulation, apoptosis and protein stability. The unconjugated SUMO-1, SUMO-2, SUMO-3 and SUMO-4 proteins localize to the nucleus. In contrast to the other SUMO proteins, SUMO-4 seems to be insensitive to sentrin-specific proteases due to the presence of Pro-90, which may impair processing to mature form and conjugation to substrates. It is suggested that defects in the gene that encodes for the SUMO-4 protein may be involved in the pathogenesis of type I diabetes.
Background References
1. Song G.G., et al. 2012. Association between the SUMO4 M55V (A163G) polymorphism and susceptibility to type 1 diabetes: a meta-analysis. Hum. Immunol. 73:1055-1059.
2. Park G., et al. 2012. SUMO4 C438T polymorphism is associated with papulopustular skin lesion in Korean patients with Behcet\'s disease. Rheumatol. Int. 32:3031-3037.
Sequence Similarity
Belongs to the ubiquitin family. SUMO subfamily.
Tissue Specificity
Expressed mainly in adult and embryonic kidney. Expressed at various levels in immune tissues, with the highest expression in the lymph node and spleen.
Post-translational Modification
In contrast to SUMO1, SUMO2 and SUMO3, seems to be insensitive to sentrin-specific proteases due to the presence of Pro-90. This may impair processing to mature form and conjugation to substrates.
Western blot analysis of SUMO4 on different lysates with Rabbit anti-SUMO4 antibody (ET1701-8) at 1/2,000 dilution.
Lane 1: HeLa cell lysate Lane 2: A431 cell lysate Lane 3: RAW264.7 cell lysate Lane 4: Neuro-2a cell lysate Lane 5: PC-12 cell lysate
Lysates/proteins at 20 µg/Lane.
Predicted band size: 11 kDa Observed band size: 18 kDa
Exposure time: 3 minutes; ECL: K1801;
4-20% SDS-PAGE gel.
Proteins were transferred to a PVDF membrane and blocked with 5% NFDM/TBST for 1 hour at room temperature. The primary antibody (ET1701-8) at 1/2,000 dilution was used in primary antibody dilution (K1803) at 4℃ overnight. Goat Anti-Rabbit IgG - HRP Secondary Antibody (HA1001) at 1/50,000 dilution was used for 1 hour at room temperature.
ICC staining of SUMO4 in 293 cells (green). Formalin fixed cells were permeabilized with 0.1% Triton X-100 in TBS for 10 minutes at room temperature and blocked with 10% negative goat serum for 15 minutes at room temperature. Cells were probed with the primary antibody (ET1701-8, 1/50) for 1 hour at room temperature, washed with PBS. Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG was used as the secondary antibody at 1/1,000 dilution. The nuclear counter stain is DAPI (blue).
ICC staining of SUMO4 in MCF-7 cells (green). Formalin fixed cells were permeabilized with 0.1% Triton X-100 in TBS for 10 minutes at room temperature and blocked with 10% negative goat serum for 15 minutes at room temperature. Cells were probed with the primary antibody (ET1701-8, 1/50) for 1 hour at room temperature, washed with PBS. Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG was used as the secondary antibody at 1/1,000 dilution. The nuclear counter stain is DAPI (blue).
ICC staining of SUMO4 in HepG2 cells (green). Formalin fixed cells were permeabilized with 0.1% Triton X-100 in TBS for 10 minutes at room temperature and blocked with 10% negative goat serum for 15 minutes at room temperature. Cells were probed with the primary antibody (ET1701-8, 1/50) for 1 hour at room temperature, washed with PBS. Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG was used as the secondary antibody at 1/1,000 dilution. The nuclear counter stain is DAPI (blue).
ICC staining of SUMO4 in RH-35 cells (green). Formalin fixed cells were permeabilized with 0.1% Triton X-100 in TBS for 10 minutes at room temperature and blocked with 10% negative goat serum for 15 minutes at room temperature. Cells were probed with the primary antibody (ET1701-8, 1/50) for 1 hour at room temperature, washed with PBS. Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG was used as the secondary antibody at 1/1,000 dilution. The nuclear counter stain is DAPI (blue).
Flow cytometric analysis of SUMO4 was done on 293 cells. The cells were fixed, permeabilized and stained with the primary antibody (ET1701-8, 1/50) (red). After incubation of the primary antibody at room temperature for an hour, the cells were stained with a Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG Secondary antibody at 1/1000 dilution for 30 minutes.Unlabelled sample was used as a control (cells without incubation with primary antibody; black).
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