Back to Search
Start Over
Isolation and characterization of a GTPase activating protein specific for the Rab3 subfamily of small G proteins.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 1997 Feb 21; Vol. 272 (8), pp. 4655-8. - Publication Year :
- 1997
-
Abstract
- The Rab small G protein family, consisting of nearly 30 members, is implicated in intracellular vesicle trafficking. They cycle between the GDP-bound and GTP-bound forms, and the latter is converted to the former by the action of a GTPase activating protein (GAP). No GAP specific for each Rab family member or Rab subfamily has been isolated in mammal. Here we purified a GAP with Rab3A as a substrate from rat brain. The purified protein was specifically active on the Rab3 subfamily members (Rab3A, -B, -C, and -D). Of this subfamily, Rab3A and -C are implicated in Ca2+-dependent exocytosis, particularly in neurotransmitter release. This GAP, named Rab3 GAP, was active on the lipid-modified form, but not on the lipid-unmodified form. Rab3 GAP showed a minimum molecular mass of about 130 kDa on SDS-polyacrylamide gel electrophoresis. We cloned its cDNA from a human brain cDNA library, and the isolated cDNA encoded a protein with a Mr of 110,521 and 981 amino acids, which showed no homology to any known protein. The recombinant protein exhibited GAP activity toward the Rab3 subfamily members, and the catalytic domain was located at the C-terminal region. Northern blot analysis indicated that Rab3 GAP was ubiquitously expressed.
- Subjects :
- Animals
Brain metabolism
Enzyme Activation
GTPase-Activating Proteins
Humans
Proteins genetics
Proteins metabolism
Rats
Recombinant Proteins genetics
Recombinant Proteins isolation & purification
Recombinant Proteins metabolism
rab3 GTP-Binding Proteins
GTP Phosphohydrolases metabolism
GTP-Binding Proteins metabolism
Proteins isolation & purification
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 272
- Issue :
- 8
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 9030515
- Full Text :
- https://doi.org/10.1074/jbc.272.8.4655