{"database":"biostudies-literature","file_versions":[],"scores":{"citationCount":0,"reanalysisCount":0,"viewCount":46,"searchCount":0},"additional":{"submitter":["Segawa K"],"funding":["Ministry of Education, Culture, Sports, Science and Technology"],"pagination":["7722-7739"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC6514636"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["294(19)"],"pubmed_abstract":["Membrane tethering is a highly regulated event occurring during the initial physical contact between membrane-bounded transport carriers and their target subcellular membrane compartments, thereby ensuring the spatiotemporal specificity of intracellular membrane trafficking. Although Rab-family small GTPases and specific Rab-interacting effectors, such as coiled-coil tethering proteins and multisubunit tethering complexes, are known to be involved in membrane tethering, how these protein components directly act upon the tethering event remains enigmatic. Here, using a chemically defined reconstitution system, we investigated the molecular basis of membrane tethering by comprehensively and quantitatively evaluating the intrinsic capacities of 10 representative human Rab-family proteins (Rab1a, -3a, -4a, -5a, -6a, -7a, -9a, -11a, -27a, and -33b) to physically tether two distinct membranes via homotypic and heterotypic Rab-Rab assembly. All of the Rabs tested, except Rab27a, specifically caused homotypic membrane tethering at physiologically relevant Rab densities on membrane surfaces (<i>e.g.</i> Rab/lipid molar ratios of 1:100-1:3,000). Notably, endosomal Rab5a retained its intrinsic potency to drive efficient homotypic tethering even at concentrations below the Rab/lipid ratio of 1:3,000. Comprehensive reconstitution experiments further uncovered that heterotypic combinations of human Rab-family isoforms, including Rab1a/6a, Rab1a/9a, and Rab1a/33b, can directly and selectively mediate membrane tethering. Rab1a and Rab9a in particular synergistically triggered very rapid and efficient membrane tethering reactions through their heterotypic <i>trans</i>-assembly on two opposing membranes. In conclusion, our findings establish that, in the physiological context, homotypic and heterotypic <i>trans</i>-assemblies of Rab-family small GTPases can provide the essential molecular machinery necessary to drive membrane tethering in eukaryotic endomembrane systems."],"journal":["The Journal of biological chemistry"],"pubmed_title":["Homotypic and heterotypic <i>trans</i>-assembly of human Rab-family small GTPases in reconstituted membrane tethering."],"pmcid":["PMC6514636"],"funding_grant_id":["Grants-in-Aid for Scientific Research"],"pubmed_authors":["Mima J","Tamura N","Segawa K"],"view_count":["46"],"additional_accession":[]},"is_claimable":false,"name":"Homotypic and heterotypic <i>trans</i>-assembly of human Rab-family small GTPases in reconstituted membrane tethering.","description":"Membrane tethering is a highly regulated event occurring during the initial physical contact between membrane-bounded transport carriers and their target subcellular membrane compartments, thereby ensuring the spatiotemporal specificity of intracellular membrane trafficking. Although Rab-family small GTPases and specific Rab-interacting effectors, such as coiled-coil tethering proteins and multisubunit tethering complexes, are known to be involved in membrane tethering, how these protein components directly act upon the tethering event remains enigmatic. Here, using a chemically defined reconstitution system, we investigated the molecular basis of membrane tethering by comprehensively and quantitatively evaluating the intrinsic capacities of 10 representative human Rab-family proteins (Rab1a, -3a, -4a, -5a, -6a, -7a, -9a, -11a, -27a, and -33b) to physically tether two distinct membranes via homotypic and heterotypic Rab-Rab assembly. All of the Rabs tested, except Rab27a, specifically caused homotypic membrane tethering at physiologically relevant Rab densities on membrane surfaces (<i>e.g.</i> Rab/lipid molar ratios of 1:100-1:3,000). Notably, endosomal Rab5a retained its intrinsic potency to drive efficient homotypic tethering even at concentrations below the Rab/lipid ratio of 1:3,000. Comprehensive reconstitution experiments further uncovered that heterotypic combinations of human Rab-family isoforms, including Rab1a/6a, Rab1a/9a, and Rab1a/33b, can directly and selectively mediate membrane tethering. Rab1a and Rab9a in particular synergistically triggered very rapid and efficient membrane tethering reactions through their heterotypic <i>trans</i>-assembly on two opposing membranes. In conclusion, our findings establish that, in the physiological context, homotypic and heterotypic <i>trans</i>-assemblies of Rab-family small GTPases can provide the essential molecular machinery necessary to drive membrane tethering in eukaryotic endomembrane systems.","dates":{"release":"2019-01-01T00:00:00Z","publication":"2019 May","modification":"2024-02-15T09:42:51.869Z","creation":"2020-11-08T08:56:09Z"},"accession":"S-EPMC6514636","cross_references":{"pubmed":["30910814"],"doi":["10.1074/jbc.ra119.007947","10.1074/jbc.RA119.007947"]}}