Characterization of GAPCenA, a GTPase activating protein for Rab6, part of which associates with the centrosome.
The Rab6 GTPase regulates intracellular transport at the level of the Golgi apparatus, probably in a retrograde direction. Here, we report the identification and characterization of a novel human Rab6-interacting protein named human GAPCenA (for 'GAP and centrosome-associated'). Primary sequence analysis indicates that GAPCenA displays similarities, within a central 200 amino acids domain, to both the yeast Rab GTPase activating proteins (GAPs) and to the spindle checkpoint proteins Saccharomyces cerevisiae Bub2p and Schizosaccharomyces pombe Cdc16p. We demonstrate that GAPCenA is indeed a GAP, specifically active in vitro on Rab6 and, to a lesser extent, on Rab4 and Rab2 proteins. Immunofluorescence and cell fractionation experiments showed that GAPCenA is mainly cytosolic but that a minor pool is associated with the centrosome. Moreover, GAPCenA was found to form complexes with cytosolic gamma-tubulin and to play a role in microtubule nucleation. Therefore, GAPCenA may be involved in the coordination of microtubule and Golgi dynamics during the cell cycle.
Cuif
M H
MH
UMR CNRS 144 et 168, Institut Curie, 26 Rue d'Ulm, 75248 Paris Cedex 05, France.
Possmayer
F
F
Zander
H
H
Bordes
N
N
Jollivet
F
F
Couedel-Courteille
A
A
Janoueix-Lerosey
I
I
Langsley
G
G
Bornens
M
M
Goud
B
B
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D018385:Centrosome / Q000378:metabolism*; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012568:Schizosaccharomyces / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D020691:rab GTP-Binding Proteins; D020703:ras GTPase-Activating Proteins; D018631:ras Proteins / Q000378:metabolism*
D002352:Carrier Proteins; D017931:DNA Primers; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D008869:Microtubule-Associated Proteins; D011506:Proteins; C119053:RABGAP1 protein, human; C094135:Rab6 protein; D011994:Recombinant Proteins; D014404:Tubulin; D020703:ras GTPase-Activating Proteins; D020558:GTP Phosphohydrolases; D020691:rab GTP-Binding Proteins; D018631:ras Proteins