Identification and characterisation of novel Mss4-binding Rab GTPases
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Identification and characterisation of novel Mss4-binding Rab GTPases. / Wixler, Viktor; Wixler, Ludmilla; Altenfeld, Anika; Ludwig, Stephan; Goody, Roger S; Itzen, Aymelt.
in: BIOL CHEM, Jahrgang 392, Nr. 3, 03.2011, S. 239-48.Publikationen: SCORING: Beitrag in Fachzeitschrift/Zeitung › SCORING: Zeitschriftenaufsatz › Forschung › Begutachtung
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TY - JOUR
T1 - Identification and characterisation of novel Mss4-binding Rab GTPases
AU - Wixler, Viktor
AU - Wixler, Ludmilla
AU - Altenfeld, Anika
AU - Ludwig, Stephan
AU - Goody, Roger S
AU - Itzen, Aymelt
PY - 2011/3
Y1 - 2011/3
N2 - 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.
AB - 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.
KW - Amino Acid Sequence
KW - Animals
KW - Fluorescent Antibody Technique
KW - Guanine Nucleotide Exchange Factors
KW - HEK293 Cells
KW - Humans
KW - Mice
KW - Molecular Chaperones
KW - Molecular Sequence Data
KW - Mutation
KW - NIH 3T3 Cells
KW - Protein Binding
KW - rab GTP-Binding Proteins
KW - Journal Article
KW - Research Support, Non-U.S. Gov't
U2 - 10.1515/BC.2011.022
DO - 10.1515/BC.2011.022
M3 - SCORING: Journal article
C2 - 21194374
VL - 392
SP - 239
EP - 248
JO - BIOL CHEM
JF - BIOL CHEM
SN - 1431-6730
IS - 3
ER -