title: Lck unique domain influences Lck specificity and biological function.
abstract: Src-family tyrosine kinases share structural and amino acid sequence homology, particularly in the catalytic domain as well as in the SH2 and SH3 domains of the regulatory region. However, each src-family member also contains a unique domain which is specific to and characteristic of each individual tyrosine kinase. These unique or specific domains may contribute to the functional specificity of each src-family kinase. To address this possibility, we analyzed the kinase activities and substrate specificities of the lymphoid src-kinase, pp56lck, and a mutant of pp56lck lacking its specific domain. Our data show that both the wild type enzyme and the specific domain-deleted mutant displayed similar affinities for ATP and the non-physiological substrate denatured enolase. However, the specific domain-deleted mutant failed to phosphorylate a number of physiological substrates of pp56lck. In addition, the ability of pp56lck to mediate induction of the interleukin-2 promoter was strongly impaired upon deletion of its specific domain. Thus, the unique domain is not required for the intrinsic kinase activity of pp56lck, however, it influences substrate preference and contributes to the unique physiological function of this src-family tyrosine kinase.
authors.affiliation: Centro Nacional de Biotecnología, Universidad Autonoma, Campus de Cantoblanco, Madrid, Spain.
authors.forename: A C
authors.initials: AC
authors.lastname: Carrera
authors.forename: H
authors.initials: H
authors.lastname: Paradis
authors.forename: L R
authors.initials: LR
authors.lastname: Borlado
authors.forename: T M
authors.initials: TM
authors.lastname: Roberts
authors.forename: C
authors.initials: C
authors.lastname: Martinez
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics; D007700:Kinetics; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D019000:Phosphotyrosine; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017384:Sequence Deletion; D013379:Substrate Specificity; D013601:T-Lymphocytes / Q000201:enzymology; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D017931:DNA Primers; D007376:Interleukin-2; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)