Molecular features of human ubiquitin-like SUMO genes and their encoded proteins.
The SUMO (small ubiquitin-like modifier) protein and ubiquitin have similar 3-D structure. Sumolyzation and ubiquitination exhibit similar biological processes for post-translational modification. However, unlike ubiquitination, which targets proteins for degradation, sumolyzation participates in a number of cellular processes such as nuclear transport, transcriptional regulation, apoptosis and protein stability. The human genome contains three SUMO-1/2/3 functional genes, as well as eight SUMO-1 pseudogenes and 23 SUMO-2 pseudogenes, but no SUMO-3 pseudogenes. The protein-coding sequence of the SUMO-1 gene is interrupted by four introns, while those of SUMO-2 and SUMO-3 genes are interrupted by three introns. Human SUMO-1 protein exhibits 44% sequence identity with SUMO-2 and SUMO-3 proteins, while SUMO-2 and SUMO-3 proteins share 86% sequence identity. Phylogenetic analyses indicate that the SUMO-3 gene was derived from the SUMO-2 gene. SUMO-1 mRNA appears to be most abundant in human epithelial HeLa, kidney 293 and neuronal NT2 cells, while the SUMO-3 mRNA seems to be much less abundant than SUMO-2 mRNA, especially in HeLa and 293 cells. Many cellular proteins of high molecular weights were covalently modified by SUMO-1/2/3 proteins. However, some free form of SUMO-2/3 proteins was also detected. Most SUMO-1/2/3 proteins were shown to be localized on nuclear membrane, nuclear bodies and cytoplasm, respectively.
Su
Hong-Lin
HL
Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC.
Li
Steven S-L
SS
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D019143:Evolution, Molecular; D005091:Exons; D015870:Gene Expression; D005796:Genes / Q000235:genetics; D015894:Genome, Human; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D009685:Nuclear Envelope / Q000378:metabolism; D010802:Phylogeny; D011506:Proteins / Q000378:metabolism; D011544:Pseudogenes / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism
D011506:Proteins; D012333:RNA, Messenger; D025842:SUMO-1 Protein; C117909:SUMO2 protein, human; C492189:SUMO3 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D014452:Ubiquitins