Premium
A lysine in the ATP‐binding site of P130gag‐fps is essential for protein‐tyrosine kinase activity.
Author(s) -
Weinmaster G.,
Zoller M.J.,
Pawson T.
Publication year - 1986
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1986.tb04179.x
Subject(s) - biology , lysine , biochemistry , tyrosine kinase , tyrosine , microbiology and biotechnology , signal transduction , amino acid
The P130gag‐fps transforming protein of Fujinami sarcoma virus (FSV) possesses tyrosine‐specific protein kinase activity and autophosphorylates at Tyr‐1073. Within the kinase domain of P130gag‐fps is a putative ATP‐binding site containing a lysine (Lys‐950) homologous to lysine residues in cAMP‐dependent protein kinase and p60v‐src which bind the ATP analogue p‐fluorosulfonylbenzoyl‐5′ adenosine. FSV mutants in which the codon for Lys‐950 has been changed to codons for arginine or glycine encode metabolically stable but enzymatically defective proteins which are unable to effect neoplastic transformation. Kinase‐defective P130gag‐fps containing arginine at residue 950 was normally phosphorylated at serine residues in vivo suggesting that this amino acid substitution has a minimal effect on protein folding and processing. The inability of arginine to substitute for lysine at residue 950 suggests that the side chain of Lys‐950 is essential for P130gag‐fps catalytic activity, probably by virtue of a specific interaction with ATP at the phosphotransfer active site. Tyr‐1073 of the Arg‐950 P130gag‐fps mutant protein was not significantly autophosphorylated either in vitro or in vivo, but could be phosphorylated in trans by enzymatically active P140gag‐fps. These data indicate that Tyr‐1073 can be modified by intermolecular autophosphorylation.