Os01g0100100

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Annotated Information

Function

• Rab GTPase involved in membrane transport. They are important regulators in plasma membrane traffic and multivesicular membrane transport.The performance of its function is combined with the cycle between GTP and GDP conformations. In their activated, GTP-bound state, RAB GTPases localize at membranes, where they recruit effector molecules and promote downstream reactions including tethering of transport vesicles or organelles to target membranes required for docking and fusion. Hydrolysis of GTP causes the release of RAB GTPases into the cytosol in a RAB GDP dissociation inhibitor-dependent manner.Activation and inactivation of GTPases are regulated by guanine nucleotide exchange factors and by GTPase activating proteins; these regulators drive the GTPase cycle of RAB proteins.
• In addition to the plasm membrane, Rab GTPase also participates in the transport of the proglutelin from the Golgi to the protein storage vacuole (PSV). Also, it functions in keeping the general structural organization of the endomembrane system in developing rice seeds.
• The gene RabGAP22 in Arabidopsis, a Rab GTPase-activating protein, is homologous to this gene in rice, but it plays a crucial role in regulating multiple responses. Its expression was found to be associated with elevated endogenous levels of the plant hormones jasmonic acid (JA) and abscisic acid (ABA).

Expression

• This gene is expressed in leaf epidermal cells, root, vascular tissues and stomata, with a molecular mass of 20–25 kDa.

Evolution

• The average G+C content in rice is higher than in Arabidopsis, but there are no any CpG islands in chromosome 1, indicating a neutral nucleotide distribution in this region. Also, there are a lot of tandem repeats. Some predicted genes were functionally characterized by homology to known proteins using BLASTP. All most all of these genes are also found in Arabidopsis.
• This gene encodes Putative GTPase-activating protein, and molecular function is Rab GTPase activator activity, which is homologous with Arabidopsis thaliana. Also, it is conserved in human, chimpanzee, Rhesus monkey, dog, cow, mouse, rat, chicken, zebrafish, fruit fly, mosquito, C.elegans, S.pombe, rice, and frog, and this gene is the one of this super-gene family.http://www.ncbi.nlm.nih.gov/gene/827007

Labs working on this gene

• Ilse Foissner: Plant Physiology/Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria. E-mail: Ilse.Foissner@sbg.ac.at.
• Toshihiro Kumamaru: Faculty of Agriculture, Kyushu University, Fukuoka 812–8581, Japan. E-mail: kumamaru@agr.kyushu-u.ac.jp.

References

1. Hoepflinger, M.C., Geretschlaeger, A., Sommer, A., et al. Molecular and biochemical analysis of the first ARA6 homologue, a RAB5 GTPase, from green algae[J]. Journal of Experimental Botany, 2013, 10: 2-16.
2. Goh T, Uchida W, Arakawa S, et al. VPS9a, the common activator for two distinct types of RAB5 GTPases, is essential for the development of Arabidopsis thaliana[J]. Plant Cell, 2007, 19: 3504-3515.
3. Saito C, Ueda T. 2009. Functions of RAB and SNARE Proteins in Plant Life. In: Kwang WJ, ed. International Review of Cell and Molecular Biology, Vol. 274. Academic Press, 183–233.
4. Fukuda, M., Satoh-Cruz, M., Wen, L.Y., et al. The Small GTPase Rab5a Is Essential for Intracellular Transport of Proglutelin from the Golgi Apparatus to the Protein Storage Vacuole and Endosomal Membrane Organization in Developing Rice Endosperm[J]. Plant Physiology, 2011, 157: 632-644.
5. Roos, J., Bejai, S., Oide, S. & Christina D.. RabGAP22 Is Required for Defense to the Vascular Pathogen Verticillium longisporum and Contributes to Stomata Immunity[J]. PLOS ONE, 2014, 9(2): 1-14.
6. Schwartz S.L., Cao C., Pylypenko O., et al. RAB GTPases at a glance[J]. Journal of Cell Science, 2007, 120: 3905–3910.
7. Takuji Sasaki, Takashi Matsumoto, Kimiko Yamamoto, et al. The genome sequence and structure of rice chromosome 1[J]. Nature, 2002, 420:312-316.