RAB18 explained

Ras-related protein Rab-18 is a protein that in humans is encoded by the RAB18 gene.^{[1] [2]} It is a member of the Rab family of Ras-related small GTPases.^[3]

Rab18 is a ubiquitously expressed protein with particularly high expression in the brain.^[4] Rab18 was first characterised as an endosomal protein in epithelial cells of mouse kidney and intestines.^[4] Subsequent studies revealed that Rab18 has a wide intracellular distribution; localising to the Golgi complex, endoplasmic reticulum, lipid droplets, and cytosol of various cell types.^{[3] [5] [6]} In the brain, Rab18 has been isolated in association with synaptic vesicles^{[7] [8]} and has been observed to localise to secretory granules in neuroendocrine cells.^[9]

Mutations in RAB18, RAB3GAP1, RAB3GAP2, or TBC1D20 are thought to cause Warburg Micro syndrome by disrupting RAB18 function. RAB3GAP1, RAB3GAP2, and TBC1D20 genes offer instructions for creating proteins that regulate RAB18.^[10] The RAB3GAP1 and RAB3GAP2 proteins interact and create a guanine–nucleotide exchange factor complex that activates RAB18. The TBC1D20 protein may inactivate RAB18 by acting as a GTPase-activating protein for it.^{[10] [11]}

Further reading

• Adams MD, Kerlavage AR, Fleischmann RD, etal . Initial assessment of human gene diversity and expression patterns based upon 83 million nucleotides of cDNA sequence. . Nature . 377 . 6547 Suppl . 3–174 . 1995 . 7566098 . .
• Maruyama K, Sugano S . Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides. . Gene . 138 . 1–2 . 171–4 . 1994 . 8125298 . 10.1016/0378-1119(94)90802-8 .
• Hillier LD, Lennon G, Becker M, etal . Generation and analysis of 280,000 human expressed sequence tags. . Genome Res. . 6 . 9 . 807–28 . 1997 . 8889549 . 10.1101/gr.6.9.807 . free .
• Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, etal . Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library. . Gene . 200 . 1–2 . 149–56 . 1997 . 9373149 . 10.1016/S0378-1119(97)00411-3 .
• Hu RM, Han ZG, Song HD, etal . Gene expression profiling in the human hypothalamus-pituitary-adrenal axis and full-length cDNA cloning. . Proc. Natl. Acad. Sci. U.S.A. . 97 . 17 . 9543–8 . 2000 . 10931946 . 10.1073/pnas.160270997 . 16901 . 2000PNAS...97.9543H . free .
• Hartley JL, Temple GF, Brasch MA . DNA cloning using in vitro site-specific recombination. . Genome Res. . 10 . 11 . 1788–95 . 2001 . 11076863 . 10.1101/gr.143000. 310948 .
• Wiemann S, Weil B, Wellenreuther R, etal . Toward a catalog of human genes and proteins: sequencing and analysis of 500 novel complete protein coding human cDNAs. . Genome Res. . 11 . 3 . 422–35 . 2001 . 11230166 . 10.1101/gr.GR1547R . 311072 .
• Simpson JC, Wellenreuther R, Poustka A, etal . Systematic subcellular localization of novel proteins identified by large-scale cDNA sequencing. . EMBO Rep. . 1 . 3 . 287–92 . 2001 . 11256614 . 10.1093/embo-reports/kvd058 . 1083732 .
• Strausberg RL, Feingold EA, Grouse LH, etal . Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. . Proc. Natl. Acad. Sci. U.S.A. . 99 . 26 . 16899–903 . 2003 . 12477932 . 10.1073/pnas.242603899 . 139241 . 2002PNAS...9916899M . free .
• Behrends U, Schneider I, Rössler S, etal . Novel tumor antigens identified by autologous antibody screening of childhood medulloblastoma cDNA libraries. . Int. J. Cancer . 106 . 2 . 244–51 . 2003 . 12800201 . 10.1002/ijc.11208 . 36836051 . free .
• Ota T, Suzuki Y, Nishikawa T, etal . Complete sequencing and characterization of 21,243 full-length human cDNAs. . Nat. Genet. . 36 . 1 . 40–5 . 2004 . 14702039 . 10.1038/ng1285 . free .
• Deloukas P, Earthrowl ME, Grafham DV, etal . The DNA sequence and comparative analysis of human chromosome 10. . Nature . 429 . 6990 . 375–81 . 2004 . 15164054 . 10.1038/nature02462 . 2004Natur.429..375D . free .
• Gerhard DS, Wagner L, Feingold EA, etal . The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). . Genome Res. . 14 . 10B . 2121–7 . 2004 . 15489334 . 10.1101/gr.2596504 . 528928 .
• Wiemann S, Arlt D, Huber W, etal . From ORFeome to biology: a functional genomics pipeline. . Genome Res. . 14 . 10B . 2136–44 . 2004 . 15489336 . 10.1101/gr.2576704 . 528930 .
• Dou T, Ji C, Gu S, etal . Cloning and characterization of a novel splice variant of human Rab18 gene (RAB18). . DNA Seq. . 16 . 3 . 230–4 . 2006 . 16147880 . 10.1080/10425170500061681 . 45143893 .
• Mehrle A, Rosenfelder H, Schupp I, etal . The LIFEdb database in 2006. . Nucleic Acids Res. . 34 . Database issue . D415–8 . 2006 . 16381901 . 10.1093/nar/gkj139 . 1347501 .

Notes and References

1. Schafer U, Seibold S, Schneider A, Neugebauer E . Isolation and characterisation of the human rab18 gene after stimulation of endothelial cells with histamine . FEBS Lett . 466 . 1 . 148–54 . Feb 2000 . 10648831 . 10.1016/S0014-5793(99)01778-0 . 31093183 . free .
2. Web site: Entrez Gene: RAB18 RAB18, member RAS oncogene family.
3. Dejgaard SY, Murshid A, Erman A, Kizilay O, Verbich D, Lodge R, Dejgaard K, Ly-Hartig TB, Pepperkok R, Simpson JC, Presley JF . Rab18 and Rab43 have key roles in ER-Golgi trafficking . J. Cell Sci. . 121 . Pt 16 . 2768–81 . August 2008 . 18664496 . 10.1242/jcs.021808 . free .
4. Lütcke A, Parton RG, Murphy C, Olkkonen VM, Dupree P, Valencia A, Simons K, Zerial M . Cloning and subcellular localization of novel rab proteins reveals polarized and cell type-specific expression . J. Cell Sci. . 107 . 12. 3437–48 . December 1994 . 10.1242/jcs.107.12.3437 . 7706395 .
5. Martin S, Driessen K, Nixon SJ, Zerial M, Parton RG . Regulated localization of Rab18 to lipid droplets: effects of lipolytic stimulation and inhibition of lipid droplet catabolism . J. Biol. Chem. . 280 . 51 . 42325–35 . December 2005 . 16207721 . 10.1074/jbc.M506651200 . 30398568 . free .
6. Ozeki S, Cheng J, Tauchi-Sato K, Hatano N, Taniguchi H, Fujimoto T . Rab18 localizes to lipid droplets and induces their close apposition to the endoplasmic reticulum-derived membrane . J. Cell Sci. . 118 . Pt 12 . 2601–11 . June 2005 . 15914536 . 10.1242/jcs.02401 . free .
7. Burré J, Beckhaus T, Corvey C, Karas M, Zimmermann H, Volknandt W . Synaptic vesicle proteins under conditions of rest and activation: analysis by 2-D difference gel electrophoresis . Electrophoresis . 27 . 17 . 3488–96 . September 2006 . 16944461 . 10.1002/elps.200500864 . 43618245 .
8. Takamori S, Holt M, Stenius K, Lemke EA, Grønborg M, Riedel D, Urlaub H, Schenck S, Brügger B, Ringler P, Müller SA, Rammner B, Gräter F, Hub JS, De Groot BL, Mieskes G, Moriyama Y, Klingauf J, Grubmüller H, Heuser J, Wieland F, Jahn R . Molecular anatomy of a trafficking organelle . Cell . 127 . 4 . 831–46 . November 2006 . 17110340 . 10.1016/j.cell.2006.10.030 . 11858/00-001M-0000-0012-E357-D . 6703431 . free .
9. Vazquez-Martinez R, Cruz-Garcia D, Duran-Prado M, Peinado JR, Castaño JP, Malagon MM . Rab18 inhibits secretory activity in neuroendocrine cells by interacting with secretory granules . Traffic . 8 . 7 . 867–82 . July 2007 . 17488286 . 10.1111/j.1600-0854.2007.00570.x . 9987968 . free .
10. Web site: RAB18 deficiency: MedlinePlus Genetics. 27 September 2023.
11. Handley MT, Carpanini SM, Mali GR, Sidjanin DJ, Aligianis IA, Jackson IJ, FitzPatrick DR. Warburg Micro syndrome is caused by RAB18 deficiency or dysregulation. Open Biology. 5. 6. 150047. 10.1098/rsob.150047. free. 26063829. 4632505. 2015.