title: Casein kinase 2 phosphorylates recombinant human spermidine/spermine N1-acetyltransferase on both serine and threonine residues.
abstract: Casein kinase 2 purified from human erythrocyte cytosol has been found to phosphorylate human spermidine/spermine N1-acetyltransferase (SSAT) expressed as a fusion protein in E. coli and purified to homogeneity with a specific activity similar to that reported for pure human SSAT. The amino acid sequence of the protein revealed not less than four phosphorylable residues, optimal target for protein kinase 2 phosphorylation being flanked by acid residues in position +1 and +3. Our results indicate that most 32P-phosphate is taken up by Ser residues, as evidenced by HCl hydrolysis and electrophoresis and that the phosphorylation extent is modulated by the physiological polyamine concentration. Partial digestion with trypsin at a low concentration for less than one hour preferentially hydrolyzes Lys-Arg-Arg in position 141-143 of the SSAT suggesting that the Ser-phosphorylated residues are located in the C-terminus of the protein, probably Ser 146 and 149.
authors.affiliation: Dipartimento di Chimica Biologica, Universita' di Padova and Centro di Studio delle Biomembrane del CNR, via Trieste 75, Padova, 35121, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Bordin
authors.forename: C
authors.initials: C
authors.lastname: Vargiu
authors.forename: S
authors.initials: S
authors.lastname: Colombatto
authors.forename: G
authors.initials: G
authors.lastname: Clari
authors.forename: G
authors.initials: G
authors.lastname: Testore
authors.forename: A
authors.initials: A
authors.lastname: Toninello
authors.forename: M A
authors.initials: MA
authors.lastname: Grillo
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D047390:Casein Kinase II; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity; D013912:Threonine / Q000378:metabolism; D000099228:Diamine N-Acetyltransferase
chemical_list: D000123:Acetyltransferases; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D011994:Recombinant Proteins; D012694:Serine; D013912:Threonine; D000099228:Diamine N-Acetyltransferase