Ras-related protein Rab-11B is a protein that in humans is encoded by the RAB11Bgene.[1][2] Rab11b is reported as most abundantly expressed in brain, heart and testes.
Rab (Ras-related in brain) proteins form the largest section of the Ras superfamily of small GTPases. The Rab family proteins regulate intracellular membrane trafficking processes including vesicle budding, tethering, and fusion. The isoforms Rab11a, Rab11b, and Rab11c/Rab25 constitute the Rab11 subfamily based on specific sequence motifs.[3] While RAB11A is located on chromosome 15[4] and RAB11C on chromosome 1, RAB11B is placed on chromosome 19. Rab11 proteins are implicated in endocytosis and exocytosis.[5] Rab11b is reported as most abundantly expressed in brain, heart and testes.[6] Early studies with deletions of RAB11 homologs in Saccharomyces cerevisiae proved their importance in cell survival.[7][8]
Despite sharing high sequence homology, Rab11a and Rab11b appear to reside within distinct vesicle compartments.[9] Majority of Rab11b neither colocalize with transferrin receptor nor with the polymeric IgA receptor. This protein also exhibits a dependence on the microtubule cytoskeleton that is different from Rab11a.[9] High sequence diversity in the C-terminal hypervariable region is responsible for variable membrane targeting between these proteins.
Members of the Rab11 subfamily act in recycling of proteins from the endosomes to the plasma membrane, in transport of molecules from the trans-Golgi network to the plasma membrane and in phagocytosis. This subfamily also acts in polarized transport in epithelial cells.[10][11][12][13][14] Whereas most studies refer to the Rab11a isoform, little is known about Rab11b so far. Rab11b localizes predominantly in the pericentriolar recycling compartment and serves as an important component of the vesicular machinery.[15] It is required for the transfer of internalized transferrin from the recycling compartment to the plasma membrane for which active Rab11b as well as GTP hydrolysis is necessary.[15]
Structure
All Ras GTPases consist of a similar core structure and highly conserved P-loop, switch 1 and switch 2 regions. The Rab11b monomer exhibits a typical Ras-like, small GTPase fold with a six stranded β-sheet core (β1-β6) surrounded by five major α-helices (α1-α5)[12] and one minor α-helix (α6). According to the sequence similarity to other Rab GTPases can be assumed that they show closely resembling characteristics in nucleotide binding and hydrolysis. However, Rab11 isoforms could differ in hydrolysis kinetics owing to the differences in conformation, since Rab11a and Rab11b do not show an α-helical switch 2 region like other Rab GTPases. Rab11b shares 90% amino acid identity to Rab11a.[12] Kinetic experiments with Rab11a/b and Rab11-interacting proteins (FIPs) indicate that FIPs cannot differentiate between GTP-bound Rab11a and Rab11b in vitro.[16] The major divergence reveals in the inactive state. While Pasqualato et al. crystallized inactive Rab11a as a dimer in the asymmetric unit, Scapin et al. observed single crystallographically independent monomers of both the GDP- and the GppNHp-bound Rab11b structures.[12][17]
↑Zhu AX, Zhao Y, Flier JS (Dec 1994). "Molecular cloning of two small GTP-binding proteins from human skeletal muscle". Biochemical and Biophysical Research Communications. 205 (3): 1875–82. doi:10.1006/bbrc.1994.2889. PMID7811277.
↑Bhartur SG, Calhoun BC, Woodrum J, Kurkjian J, Iyer S, Lai F, Goldenring JR (Mar 2000). "Genomic structure of murine Rab11 family members". Biochemical and Biophysical Research Communications. 269 (2): 611–7. doi:10.1006/bbrc.2000.2334. PMID10708602.
↑Gromov PS, Celis JE, Hansen C, Tommerup N, Gromova I, Madsen P (Jun 1998). "Human rab11a: transcription, chromosome mapping and effect on the expression levels of host GTP-binding proteins". FEBS Letters. 429 (3): 359–64. doi:10.1016/s0014-5793(98)00607-3. PMID9662449.
↑Lai F, Stubbs L, Artzt K (Aug 1994). "Molecular analysis of mouse Rab11b: a new type of mammalian YPT/Rab protein". Genomics. 22 (3): 610–6. doi:10.1006/geno.1994.1434. PMID8001972.
↑ 9.09.1Lapierre LA, Dorn MC, Zimmerman CF, Navarre J, Burnette JO, Goldenring JR (Nov 2003). "Rab11b resides in a vesicular compartment distinct from Rab11a in parietal cells and other epithelial cells". Experimental Cell Research. 290 (2): 322–31. doi:10.1016/s0014-4827(03)00340-9. PMID14567990.
↑ 12.012.112.212.312.412.5Scapin SM, Carneiro FR, Alves AC, Medrano FJ, Guimarães BG, Zanchin NI (Jun 2006). "The crystal structure of the small GTPase Rab11b reveals critical differences relative to the Rab11a isoform". Journal of Structural Biology. 154 (3): 260–8. doi:10.1016/j.jsb.2006.01.007. PMID16545962.
↑Wang X, Kumar R, Navarre J, Casanova JE, Goldenring JR (Sep 2000). "Regulation of vesicle trafficking in madin-darby canine kidney cells by Rab11a and Rab25". The Journal of Biological Chemistry. 275 (37): 29138–46. doi:10.1074/jbc.M004410200. PMID10869360.
↑ 15.015.1Schlierf B, Fey GH, Hauber J, Hocke GM, Rosorius O (Aug 2000). "Rab11b is essential for recycling of transferrin to the plasma membrane". Experimental Cell Research. 259 (1): 257–65. doi:10.1006/excr.2000.4947. PMID10942597.
↑Pasqualato S, Senic-Matuglia F, Renault L, Goud B, Salamero J, Cherfils J (Mar 2004). "The structural GDP/GTP cycle of Rab11 reveals a novel interface involved in the dynamics of recycling endosomes". The Journal of Biological Chemistry. 279 (12): 11480–8. doi:10.1074/jbc.M310558200. PMID14699104.
↑Greenfield JP, Leung LW, Cai D, Kaasik K, Gross RS, Rodriguez-Boulan E, Greengard P, Xu H (Apr 2002). "Estrogen lowers Alzheimer beta-amyloid generation by stimulating trans-Golgi network vesicle biogenesis". The Journal of Biological Chemistry. 277 (14): 12128–36. doi:10.1074/jbc.M110009200. PMID11823458.
↑Dumanchin C, Czech C, Campion D, Cuif MH, Poyot T, Martin C, Charbonnier F, Goud B, Pradier L, Frebourg T (Jul 1999). "Presenilins interact with Rab11, a small GTPase involved in the regulation of vesicular transport". Human Molecular Genetics. 8 (7): 1263–9. doi:10.1093/hmg/8.7.1263. PMID10369872.
Maruyama K, Sugano S (Jan 1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides". Gene. 138 (1–2): 171–4. doi:10.1016/0378-1119(94)90802-8. PMID8125298.
Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, Suyama A, Sugano S (Oct 1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library". Gene. 200 (1–2): 149–56. doi:10.1016/S0378-1119(97)00411-3. PMID9373149.
Schlierf B, Fey GH, Hauber J, Hocke GM, Rosorius O (Aug 2000). "Rab11b is essential for recycling of transferrin to the plasma membrane". Experimental Cell Research. 259 (1): 257–65. doi:10.1006/excr.2000.4947. PMID10942597.
Prekeris R, Davies JM, Scheller RH (Oct 2001). "Identification of a novel Rab11/25 binding domain present in Eferin and Rip proteins". The Journal of Biological Chemistry. 276 (42): 38966–70. doi:10.1074/jbc.M106133200. PMID11481332.
Hales CM, Griner R, Hobdy-Henderson KC, Dorn MC, Hardy D, Kumar R, Navarre J, Chan EK, Lapierre LA, Goldenring JR (Oct 2001). "Identification and characterization of a family of Rab11-interacting proteins". The Journal of Biological Chemistry. 276 (42): 39067–75. doi:10.1074/jbc.M104831200. PMID11495908.
Khvotchev MV, Ren M, Takamori S, Jahn R, Südhof TC (Nov 2003). "Divergent functions of neuronal Rab11b in Ca2+-regulated versus constitutive exocytosis". The Journal of Neuroscience. 23 (33): 10531–9. PMID14627637.
Scapin SM, Carneiro FR, Alves AC, Medrano FJ, Guimarães BG, Zanchin NI (Jun 2006). "The crystal structure of the small GTPase Rab11b reveals critical differences relative to the Rab11a isoform". Journal of Structural Biology. 154 (3): 260–8. doi:10.1016/j.jsb.2006.01.007. PMID16545962.