Protein kinase C phosphorylates two of the four known syndecan cytoplasmic domains in vitro

T. Prasthofer, B. Ek, P. Ekman, R. Owens, Magnus Hook, S. Johansson

    Research output: Contribution to journalArticlepeer-review

    20 Scopus citations

    Abstract

    The transmembrane heparan sulfate proteoglycans of the syndecan family are implicated to participate in several cellular reactions which are dependent on protein kinase C. We have used an in vitro assay to assess whether any of the known syndecans may become phosphorylated directly by protein kinase C. Peptides corresponding to the complete cytoplasmic domains of rat syndecans 1 through 4 were used as substrates for the enzyme. The syndecan-2 (fibroglycan) and syndecan-3 (N-syndecan) peptides were both found to be phosphorylated by protein kinase C with Kms of 15 ± 3 μM and 85 ± 25 μM, respectively, while the syndecan-1 and -4 peptides were not phosphorylated under the conditions used. The sites of in vitro phosphorylation for syndecans-2 and -3 were localized to ser-197 and ser-339, respectively. Thus, among 13 available sites (serines and threonines) in the four peptides, two were selectively modified by the enzyme. The specificity and the kinetics of the reactions indicate that the cytoplasmic domains of syndecan-2 and -3 are likely to be physiological substrates for protein kinase C.

    Original languageEnglish (US)
    Pages (from-to)793-802
    Number of pages10
    JournalBiochemistry and Molecular Biology International
    Volume36
    Issue number4
    StatePublished - Dec 1 1995

    Keywords

    • Protein kinase C
    • Syndecan

    ASJC Scopus subject areas

    • Biochemistry
    • Genetics
    • Molecular Biology

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