Abstract
Most members of the guanosine triphosphatase (GTPase) superfamily hydrolyze guanosine triphosphate (GTP) quite slowly unless stimulated by a GTPase activating protein or GAP. The alpha subunits (G alpha) of the heterotrimeric G proteins hydrolyze GTP much more rapidly and contain an approximately 120-residue insert not found in other GTPases. Interactions between a G alpha insert domain and a G alpha GTP-binding core domain, both expressed as recombinant proteins, show that the insert acts biochemically as a GAP. The results suggest a general mechanism for GAP-dependent hydrolysis of GTP by other GTPases.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenylyl Cyclases / metabolism
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Amino Acid Sequence
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Animals
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Cell Line
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Colforsin / pharmacology
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Cyclic AMP / metabolism
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GTP Phosphohydrolases / metabolism*
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GTP-Binding Proteins / chemistry
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GTP-Binding Proteins / metabolism*
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Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
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Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
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Guanosine Triphosphate / metabolism*
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Hydrolysis
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Kinetics
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Molecular Sequence Data
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Mutation
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Protein Conformation
Substances
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Colforsin
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Guanosine 5'-O-(3-Thiotriphosphate)
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Guanosine Triphosphate
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Cyclic AMP
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GTP Phosphohydrolases
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GTP-Binding Proteins
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Adenylyl Cyclases