Positive and negative modulation of H-ras transforming potential by mutations of phenylalanine-28.
Mol Biol Rep
; 23(2): 109-17, 1996.
Article
en En
| MEDLINE
| ID: mdl-8983024
ABSTRACT
Conserved amino-acids of H-ras from residues 25 to 34 were mutated in human H-ras cDNA with a pre-existing valine-12 activating mutation ([V12]p21), and built into SV40-driven expression vectors. The influence of the introduced mutations was initially screened by transfection of Rat-1 cells to score foci of transformed cells. Non-conservative mutations of amino-acids 25 (tryptophan for glutamine), 27 (asparagine for histidine) and 34 (alanine for proline) did not abrogate the transforming potential of [V12]p21. The conservative mutation of phenylalanine-28 to tryptophan ([V12W28]p21) was also still transforming. Significantly, in the absence of the valine-12 activating mutation, tryptophan-28-ras ([W28]p21) was weakly transforming while, in contrast, [V12D28]p21 was unable to transform Rat-1 cells and retarded cell growth. Analysis of the binding and dissociation of GTP and GDP to normal and mutated p21 expressed in Escherichia coli showed that [V12D28]p21 and [D28]p21 do not bind GTP. The dissociation rate of both GTP and GDP bound to [W28]p21 is increased, suggesting a mechanism for its transforming potential in Rat-1 cells. These studies illustrate the importance of phenylalanine-28 in guanine nucleotide binding by p21H-ras. The mutations described could be valuable tools in investigations of cellular signal transduction involving small GTP-binding proteins.
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Bases de datos:
MEDLINE
Asunto principal:
Transformación Celular Neoplásica
/
Proteínas Proto-Oncogénicas p21(ras)
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Mol Biol Rep
Año:
1996
Tipo del documento:
Article
País de afiliación:
Estados Unidos