Reactivity of a sulfhydryl group of the ras oncogene product p21 modulated by GTP binding

Journal Article · Wed Nov 05 04:00:00 EST 1986 · J. Biol. Chem.; (United States)

OSTI ID:7093571

Hattori, S; Yamashita, T; Copeland, T D; Oroszlan, S; Shih, T Y

The authors have studied the sensitivity of sulfhydryl groups of a highly purified p21 protein of the v-ras/sup H/ oncogene to a thiol-specific reagent, N-ethylmaleimide (NEM). Approximately 70% of GTP binding and autokinase activities of p21 were inactivated by NEM, and excessive amounts of GTP or GDP protected p21 activities. Thiol titration revealed the presence of one fast reactive cycteine residue, the susceptibility of which is modulated by GTP binding. A total of 4 and 6 residues, respectively, became titratable upon denaturation and reduction, suggesting the presence of a disulfide bond. This GTP-modulated sulfhydryl group was identified as Cys-80 in the following tryptic peptide sequence: NH/sub 2/-Thr-Gly-Glu-Gly-Phe-Leu-Cys-Val-Phe-Ala-Ile-Asn-Asn-Thr-Lys-COOH. This is based on the comparative tryptic peptide mapping of (/sup 14/C)NEM-modified p21 in the presence and absence of GTP. The GTP-modulated peptide co-chromatographed with a synthetic peptide of the predicted sequence. Amino acid analysis of the purified (/sup 14/C)NEM-modified peptide from tryptic digests of p21 also confirmed its identity. This region of p21 shares an extensive sequence homology with various G-proteins and appears to be in the vicinity of the GTP-binding domain of these proteins.

• Research Organization: National Institutes of Health, Frederick, MD
• OSTI ID: 7093571
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 261:31; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
ANTIMITOTIC DRUGS
BIOCHEMISTRY
BIOLOGICAL EFFECTS
CARBON 14 COMPOUNDS
CHEMISTRY
DRUGS
GENES
GUANYLIC ACID
IMIDES
LABELLED COMPOUNDS
MOLECULAR STRUCTURE
NEM
NUCLEOTIDES
ONCOGENES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PROTEINS
RADIOSENSITIZERS
THIOLS
TRITIUM COMPOUNDS