Identification of phosphorylation sites in keratinocyte transglutaminase.
Article Details
- CitationCopy to clipboard
Rice RH, Mehrpouyan M, Quin Q, Phillips MA, Lee YM
Identification of phosphorylation sites in keratinocyte transglutaminase.
Biochem J. 1996 Dec 1;320 ( Pt 2):547-50.
- PubMed ID
- 8973564 [ View in PubMed]
- Abstract
Phosphorylation of keratinocyte transglutaminase occurs in its N-terminal extension and is stimulated several-fold by the protein kinase C agonist phorbol myristate acetate. In the present work, this stimulation was prevented by simultaneous treatment of the cells with the protein kinase C-selective inhibitor GF109203X. In contrast, phosphorylation occurring in the absence of phorbol ester was essentially unaffected by GF109203X, although it was decreased dramatically by the non-selective kinase inhibitor staurosporine. Four serine residues that are subject to phosphorylation have been identified by sequencing of radioactive tryptic peptides. Serines at positions 24 and 92, each containing 2-8% of the total radioactivity with or without phorbol ester stimulation, were minor sites of phosphorylation. Serine-82 was by far the dominant site of phosphorylation in the absence of phorbol ester treatment, and was also the major site in its presence. Serine-85 was phosphorylated to a high degree in the presence but not in the absence of phorbol ester stimulation. Thus the data indicate the influence of at least two different kinase activities in transglutaminase phosphorylation.