Abstract
Rab geranylgeranyl transferase (GG transferase) is a two-component enzyme that attaches 20-carbon isoprenoid groups to cysteine residues in Rab proteins, a family of guanosine triphosphate-binding proteins that regulate vesicular traffic. The mutant gene in human choroideremia, an X-linked form of retinal degeneration, encodes a protein that resembles component A of rat Rab GG transferase. Lymphoblasts from choroideremia subjects showed a marked deficiency in the activity of component A, but not component B, of Rab GG transferase. The deficiency was more pronounced when the substrate was Rab3A, a synaptic vesicle protein, than it was when the substrate was Rab1A, a protein of the endoplasmic reticulum. The data imply the existence of multiple component A proteins, one of which is missing in choroideremia.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adult
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Alkyl and Aryl Transferases*
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Cell Line, Transformed
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Cells, Cultured
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Choroid / chemistry
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Choroideremia / genetics*
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Female
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GTP-Binding Proteins / analysis
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GTP-Binding Proteins / metabolism*
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Gene Expression Regulation, Enzymologic
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Humans
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Lymphocyte Activation
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Male
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Middle Aged
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Mutation
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Nerve Tissue Proteins / analysis
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Nerve Tissue Proteins / metabolism*
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Photoreceptor Cells / chemistry
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Pigment Epithelium of Eye / chemistry
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Protein Prenylation
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Retina / chemistry
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Substrate Specificity
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Transferases / deficiency*
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Transferases / genetics
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rab1 GTP-Binding Proteins
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rab3 GTP-Binding Proteins
Substances
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Nerve Tissue Proteins
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Transferases
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Alkyl and Aryl Transferases
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Rab geranylgeranyltransferase
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GTP-Binding Proteins
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rab1 GTP-Binding Proteins
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rab3 GTP-Binding Proteins