Abstract
A subset of growth hormone-secreting human pituitary tumours carries somatic mutations that inhibit GTPase activity of a G protein alpha chain, alpha(s). The resulting activation of adenylyl cyclase bypasses the cells' normal requirement for trophic hormone. Amino acids substituted in the putative gsp oncogene identify a domain of G protein alpha-chains required for intrinsic ability to hydrolyse GTP. This domain may serve as a built-in counter-part of the separate GTPase-activating proteins required for GTP hydrolysis by small GTP-binding proteins such as p21ras.
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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Arginine / genetics
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GTP Phosphohydrolases / antagonists & inhibitors*
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GTP Phosphohydrolases / genetics
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GTP-Binding Proteins / genetics*
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GTP-Binding Proteins / metabolism
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Glutamine / genetics
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Humans
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Mutation*
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Neoplasm Proteins / genetics
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Phosphoric Monoester Hydrolases / antagonists & inhibitors*
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Pituitary Neoplasms / enzymology
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Pituitary Neoplasms / genetics*
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Proto-Oncogene Proteins / genetics
Substances
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Neoplasm Proteins
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Proto-Oncogene Proteins
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Glutamine
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Arginine
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Phosphoric Monoester Hydrolases
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GTP Phosphohydrolases
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GTP-Binding Proteins
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Adenylyl Cyclases