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Phosphorylation of basic fibroblast growth factor (FGF‐2) in the nuclei of SK‐Hep‐1 cells
Author(s) -
Vilgrain Isabelle,
Gonzalez Ana Maria,
Baird Andrew
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80342-r
Subject(s) - phosphorylation , nucleus , polyamine , chemistry , kinase , fibroblast growth factor , fibroblast , biochemistry , spermidine , protein kinase a , protein kinase c , serine , microbiology and biotechnology , enzyme , biology , in vitro , receptor
The subcellular fractions containing protein kinases capable of phosphorylating basic fibroblast growth factor (FGF‐2) are unknown, but having previously characterized one that is associated with the plasma membrane [1991, Mol. Endocrinol. 5, 1003‐1012] we evaluated the catalytic properties of another in the nucleus. The reaction is time (linear up to 15 min), enzyme (2,000–25,000 nuclei/ml), and substrate ( K m , 0.18 μM) dependent, and the targets serine. DNase pretreatment of nuclei decreases the incorporation of phosphate into FGF‐2 by 50% and the reaction. It is also inhibited by heparin (EC 50 1 μg/ml) and spermidine (EC 50 3μM). Calcium and cAMP have no effect. We conclude that the kinase is distinct from PKA, and PKC, and suggest that changes in glycosaminoglycan and polyamine concentrations during the cell cycle may modulate FGF‐2 phosphorylation in the nucleus, or as it is translocated to the nucleus.