TY - JOUR
T1 - Serine phosphorylation of syndecan-2 proteoglycan cytoplasmic domain
AU - Oh, Eok Soo
AU - Couchman, John R.
AU - Woods, Anne
N1 - Funding Information:
We thank Dr. J. T. Gallagher and his colleagues (University of Manchester, UK) for the provision of the full length and truncated syndecan-2 cDNA constructs. We also thank Dr. T. Lincoln (Department of Pathology, UAB) for help with PKA and PKG phosphorylation experiments. This work was supported in part by NIH Grant GM50194 to JRC, and by the Multipurpose Arthritis and Musculoskeletal Diseases Center at UAB, through NIH P60 Grant AR20614 to A.W.
PY - 1997/8/1
Y1 - 1997/8/1
N2 - Protein kinase C (PKC) is involved in cell-matrix and cell-cell adhesion, and the cytoplasmic domain of syndecan-2 contains two serines (residues 197 and 198) which lie in a consensus sequence for phosphorylation by PKC. Other serine and threonine residues are present but not in a consensus sequence. We investigated phosphorylation of syndecan-2 cytoplasmic domain by PKC, using purified GST-syndecan-2 fusion proteins and synthetic peptides corresponding to regions of the cytoplasmic domain. A synthetic peptide encompassing the entire cytoplasmic domain of syndecan-2 was phosphorylated by PKC with high affinity. Peptide mapping and substitution studies showed that both serines were phosphoacceptors, but each had slightly different affinity, with that of serine-197 being higher than serine-198. The efficiency of phosphorylation was concentration-dependent. At low concentrations, the cytoplasmic domain peptides were monomeric, with 2 mol/mol serine phosphorylation. At higher concentrations, however, the peptides formed dimers, with only 0.5 mol/mol phosphorylation. Concentration- dependent dimerization was not altered by phosphorylation. Phosphorylation is, therefore, dependent on the conformation of syndecan-2 cytoplasmic domain, but does not affect its oligomeric status.
AB - Protein kinase C (PKC) is involved in cell-matrix and cell-cell adhesion, and the cytoplasmic domain of syndecan-2 contains two serines (residues 197 and 198) which lie in a consensus sequence for phosphorylation by PKC. Other serine and threonine residues are present but not in a consensus sequence. We investigated phosphorylation of syndecan-2 cytoplasmic domain by PKC, using purified GST-syndecan-2 fusion proteins and synthetic peptides corresponding to regions of the cytoplasmic domain. A synthetic peptide encompassing the entire cytoplasmic domain of syndecan-2 was phosphorylated by PKC with high affinity. Peptide mapping and substitution studies showed that both serines were phosphoacceptors, but each had slightly different affinity, with that of serine-197 being higher than serine-198. The efficiency of phosphorylation was concentration-dependent. At low concentrations, the cytoplasmic domain peptides were monomeric, with 2 mol/mol serine phosphorylation. At higher concentrations, however, the peptides formed dimers, with only 0.5 mol/mol phosphorylation. Concentration- dependent dimerization was not altered by phosphorylation. Phosphorylation is, therefore, dependent on the conformation of syndecan-2 cytoplasmic domain, but does not affect its oligomeric status.
KW - Heparan sulfate proteoglycan
KW - Phosphorylation
KW - Protein kinase C
KW - Syndecan-2
UR - http://www.scopus.com/inward/record.url?scp=0031214383&partnerID=8YFLogxK
U2 - 10.1006/abbi.1997.0180
DO - 10.1006/abbi.1997.0180
M3 - Article
C2 - 9244383
AN - SCOPUS:0031214383
SN - 0003-9861
VL - 344
SP - 67
EP - 74
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1
ER -