TY - JOUR
T1 - Cyclic AMP-dependent protein kinase phosphorylates serine378 in vitronectin
AU - Mehringer, Julie H.
AU - Weigel, Carolyne J.
AU - Tollefsen, Douglas M.
N1 - Funding Information:
AcknowZe&ments --We wish to thank Mark Frazier of the Washington University Protein Chemistry Facility for sequencing the peptides. This work was supported by National Institutes of Health Grant HL-14147 (Specialized Center for Research in Thrombosis). Dr. Mehringer is a fellow of the American Heart Association, Missouri Affiliate.
PY - 1991/8/30
Y1 - 1991/8/30
N2 - We previously observed that Ser378 in the heparin-binding domain of vitronectin becomes phosphorylated by a protein kinase in plasma upon addition of ATP and divalent cations. We now report that purified plasma vitronectin contains ∼2.5 mol of phosphate per mol of protein and that vitronectin becomes phosphorylated during biosynthesis in human hepatoma (HepG2) cells. In vitro, rabbit muscle cAMP-dependent protein kinase specifically phosphorylates Ser378 in single-chain (75 kDa) vitronectin but does not phosphorylate the two-chain ( 65 10 kDa) form cleaved at Arg379. Heparin affects neither the time course nor the extent of phosphorylation of Ser378 at neutral pH. The extent of phosphorylation of Ser378 achieved with cAMP-dependent protein kinase (≥ 0.3 mol phosphate per mol vitronectin) is greater than that obtainable in plasma and should enable comparisons to be made of the activities of the native and phosphorylated forms.
AB - We previously observed that Ser378 in the heparin-binding domain of vitronectin becomes phosphorylated by a protein kinase in plasma upon addition of ATP and divalent cations. We now report that purified plasma vitronectin contains ∼2.5 mol of phosphate per mol of protein and that vitronectin becomes phosphorylated during biosynthesis in human hepatoma (HepG2) cells. In vitro, rabbit muscle cAMP-dependent protein kinase specifically phosphorylates Ser378 in single-chain (75 kDa) vitronectin but does not phosphorylate the two-chain ( 65 10 kDa) form cleaved at Arg379. Heparin affects neither the time course nor the extent of phosphorylation of Ser378 at neutral pH. The extent of phosphorylation of Ser378 achieved with cAMP-dependent protein kinase (≥ 0.3 mol phosphate per mol vitronectin) is greater than that obtainable in plasma and should enable comparisons to be made of the activities of the native and phosphorylated forms.
UR - http://www.scopus.com/inward/record.url?scp=0026052579&partnerID=8YFLogxK
U2 - 10.1016/0006-291X(91)91422-9
DO - 10.1016/0006-291X(91)91422-9
M3 - Article
C2 - 1715701
AN - SCOPUS:0026052579
SN - 0006-291X
VL - 179
SP - 655
EP - 660
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 1
ER -