Identification and characterisation of novel Mss4-binding Rab GTPases
| Autor: | Anika Altenfeld, Ludmilla Wixler, Stephan Ludwig, Viktor Wixler, Aymelt Itzen, Roger S. Goody |
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| Rok vydání: | 2011 |
| Předmět: |
Molecular Sequence Data
Clinical Biochemistry Endocytic cycle Fluorescent Antibody Technique GTPase Biochemistry Mice Animals Guanine Nucleotide Exchange Factors Humans Amino Acid Sequence Molecular Biology biology cDNA library Chemistry fungi RAB1 Cell biology HEK293 Cells rab GTP-Binding Proteins Chaperone (protein) Mutation NIH 3T3 Cells biology.protein Guanine nucleotide exchange factor Rab RAB18 Molecular Chaperones Protein Binding |
| Zdroj: | Biological Chemistry. 392 |
| ISSN: | 1437-4315 1431-6730 |
| DOI: | 10.1515/bc.2011.022 |
| Popis: | The Mss4 (mammalian suppressor of yeast Sec4) is an evolutionarily highly conserved protein and is expressed in all mammalian tissues. Although its precise biological function is still elusive, it has been shown to associate with a subset of secretory Rab proteins (Rab1b, Rab3a, Rab8a, Rab10) and to possess a rather low guanine nucleotide exchange factor (GEF) activity towards them in vitro (Rab1, Rab3a and Rab8a). By screening a human placenta cDNA library with Mss4 as bait, we identified several Rab GTPases (Rab12, Rab13 and Rab18) as novel Mss4-binding Rab proteins. Only exocytic but no endocytic Rab GTPases were found in our search. The binding of Mss4 to Rab proteins was confirmed by direct yeast two-hybrid interaction, by co-immunoprecipitation from lysates of mammalian cells, by immunofluorescence colocalisation as well as by direct in vitro binding studies. Analysis of Mss4 catalytic activity towards different Rab substrates confirmed that it is a somewhat inefficient GEF. These data, together with our mutational analysis of Mss4-Rab binding capacity, support the already proposed idea that Mss4 functions rather as a chaperone for exocytic Rab GTPases than as a GEF. |
| Databáze: | OpenAIRE |
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