Isolation and Characterization of a GTPase Activating Protein Specific for the Rab3 Subfamily of Small G Proteins
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...
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Published in | The Journal of biological chemistry Vol. 272; no. 8; pp. 4655 - 4658 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Society for Biochemistry and Molecular Biology
21.02.1997
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Subjects | |
Online Access | Get full text |
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Summary: | 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 Ca 2+ -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 M r 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. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.272.8.4655 |