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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
41
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pubmed:dateCreated |
2000-11-13
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pubmed:abstractText |
Small G proteins of the Rab family are regulators of intracellular vesicle traffic. Their intrinsic rate of GTP hydrolysis is very low but is enhanced by specific GTPase-activating proteins (GAPs) that switch G proteins to their inactive form. We have characterized the activity of recombinant Rab3-GAP on Rab3A in solution. The K(m) and K(d) values (75 microm) indicate a low affinity of Rab3-GAP for its substrate. The affinity is higher for the transition state analog Rab3A:GDP:AlF(x) (15 microm). The k(cat) (1 s(-)(1)) is within the range of values reported for other GAPs. A mutation in the switch I region of Rab3A disrupted the interaction with Rab3-GAP. Furthermore, Rabphilin, a putative target of Rab3, inhibited the activity of Rab3-GAP on Rab3. Therefore, the Rab3-GAP-binding site involves the switch I region of Rab3 and overlaps with the Rabphilin-binding domain. Substitution of a single arginine residue (Arg-728) of Rab3-GAP disrupted its catalytic activity but not its interaction with Rab3A. We propose that Rab3-GAP, like Ras- and Rho-GAPs, stabilizes the transition state of Rab3 and provides a critical arginine residue to accelerate the GTPase reaction.
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Aluminum Compounds,
http://linkedlifedata.com/resource/pubmed/chemical/Arginine,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Calmodulin,
http://linkedlifedata.com/resource/pubmed/chemical/Fluorides,
http://linkedlifedata.com/resource/pubmed/chemical/GTP-Binding Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/GTPase-Activating Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Guanine Nucleotides,
http://linkedlifedata.com/resource/pubmed/chemical/Guanosine Triphosphate,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Fusion Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/aluminum fluoride,
http://linkedlifedata.com/resource/pubmed/chemical/rab3 GTP-Binding Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/rab3A GTP-Binding Protein,
http://linkedlifedata.com/resource/pubmed/chemical/ras GTPase-Activating Proteins
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pubmed:status |
MEDLINE
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pubmed:month |
Oct
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pubmed:issn |
0021-9258
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
13
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pubmed:volume |
275
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
31786-91
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:10859313-Aluminum Compounds,
pubmed-meshheading:10859313-Amino Acid Sequence,
pubmed-meshheading:10859313-Animals,
pubmed-meshheading:10859313-Arginine,
pubmed-meshheading:10859313-Binding Sites,
pubmed-meshheading:10859313-Calcium,
pubmed-meshheading:10859313-Calmodulin,
pubmed-meshheading:10859313-Catalysis,
pubmed-meshheading:10859313-Fluorides,
pubmed-meshheading:10859313-GTP-Binding Proteins,
pubmed-meshheading:10859313-GTPase-Activating Proteins,
pubmed-meshheading:10859313-Guanine Nucleotides,
pubmed-meshheading:10859313-Guanosine Triphosphate,
pubmed-meshheading:10859313-Kinetics,
pubmed-meshheading:10859313-Molecular Sequence Data,
pubmed-meshheading:10859313-Mutation,
pubmed-meshheading:10859313-Protein Binding,
pubmed-meshheading:10859313-Recombinant Fusion Proteins,
pubmed-meshheading:10859313-Sequence Alignment,
pubmed-meshheading:10859313-Substrate Specificity,
pubmed-meshheading:10859313-Thermodynamics,
pubmed-meshheading:10859313-rab3 GTP-Binding Proteins,
pubmed-meshheading:10859313-rab3A GTP-Binding Protein,
pubmed-meshheading:10859313-ras GTPase-Activating Proteins
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pubmed:year |
2000
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pubmed:articleTitle |
Biochemical characterization of Rab3-GTPase-activating protein reveals a mechanism similar to that of Ras-GAP.
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pubmed:affiliation |
CNRS UPR 1929, Institut de Biologie Physico-Chimique, 13 rue P. et M. Curie, 75005 Paris, France.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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