Title: Phorbol ester stimulates the synthesis and phosphorylation of a 48 kDa-intracellular protein in plasminogen activator secreting melanoma cells
Authors: Bosman, F ×
Opdenakker, Ghislain
Van Damme, Jozef
Billiau, Alfons #
Issue Date: May-1986
Series Title: Biochemical and Biophysical Research Communications vol:137 issue:1 pages:263-72
Abstract: Phorbol ester (12-O-tetradecanoyl-phorbol 13-acetate) stimulates the secretion of tissue-type plasminogen activator by the melanoma cell line, Bowes. This effect is associated with increased levels of mRNAs for both tissue-type plasminogen activator and a 48 kDa-protein. Labelling of melanoma cells with L-[35S]methionine allowed to identify an intracellular protein which, by 3 criteria, was identical with the in vitro translation product of the 48kDa-protein mRNA: a Mr of 48,000 on electrophoresis in the presence of sodium dodecyl sulphate; inducibility by phorbol ester and failure of reducing agents to affect electrophoretic mobility. As detectable by L-[35S]methionine labelling, the protein was mainly localized in the cytosol. In vitro phosphorylation reactions, carried out on subcellular fractions revealed a membrane-associated protein which also had the three characteristics of the aforementioned 48 kDa-protein. Phosphorylation did not require Ca2+-ions. Addition of phorbol ester to the reaction mixtures increased the phosphorylation. Reconstitution experiments between membrane and cytosol fractions of phorbol ester-treated and untreated cells showed that the 48kDa protein occurs in a cytosolic, unphosphorylated and a membrane-bound, phosphorylated form and that the former is converted to the latter by a phorbol ester activated, membrane-associated protein kinase.
ISSN: 0006-291X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Molecular Immunology (Rega Institute)
Academic Center for General Practice
Laboratory of Immunobiology (Rega Institute)
× corresponding author
# (joint) last author

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