1,720,969 research outputs found
Role of phosphorylated aminoacyl residues in generating atypical consensus sequences which are recognized by casein kinase-2 but not by casein kinase-1.
No full textA synthetic beta-casein phosphopeptide and analogues as model substrates for casein kinase-1, a ubiquitous, phosphate directed protein kinase.
No full textEfficient Fmoc/solid-phase peptide synthesis of O-phosphotyrosyl-containing peptides and their use as phosphatase substrates.
No full textPartially dephosphorylated phosphopeptide AcSer(P)-Ser(P)-Ser(P) is an excellent substrate for casein kinase-2.
No full textPhosphotyrosine specifies the phosphorylation by protein kinase CK2 of a peptide reproducing the activation loop of the insulin receptor protein tyrosine kinase.
No full textProtein kinase CK2 is a ubiquitous Ser/Thr-specific protein kinase responsible for the phosphorylation of many proteins implicated in signal transduction. It phosphorylates both threonyl and seryl residue(s) of the insulin receptor beta-subunit. In this study, a series of peptides, reproducing all the threonyl sites of the intracellular domain of the insulin receptor that display the consensus sequence for CK2, has been synthesized and used as substrate for purified rat liver CK2. The only peptide readily phosphorylated is the one reproducing the activation loop of the insulin receptor (EIYET1160DYYA), including three tyrosines (Y1158, Y1162 and Y1163) whose phosphorylation through an intermolecular autocatalytic process promotes the activation of the receptor kinase. The phosphorylation efficiency of T1160 is increased almost 20-fold if these three tyrosines are previously phosphorylated. By using variably phosphorylated peptides, the tyrosine mainly responsible for such a hierarchical phosphorylation process has been identified as Y1163. It can be concluded, from these data, that T1160 situated in the activation loop of the insulin receptor, represents an excellent target for CK2, its phosphorylation being triggered by the previous autophosphorylation of the three tyrosyl residues surrounding it, with special reference to Y1163. These data are consistent with the implication of CK2 in the regulation of the activation process of the insulin receptor protein tyrosine kinase
The comparative efficiencies of the Ser(P)-, Thr(P)- and Tyr(P)-residues as specificity determinants for casein kinase-1.
No full textSynthetic fragments of beta-casein as model substrates for liver and mammary gland casein kinases.
No full textThe effect of polylysine on casein-kinase-2 activity is influenced by both the structure of the protein/peptide substrates and the subunit composition of the enzyme.
No full textPhosphorylation of src-phosphopeptides by casein kinases-1 and -2: favourable effect of phosphotyrosine.
No full textSynthetic peptides as model substrates for the study of the specificity of the polycation-stimulated protein phosphatases.
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