title: A nerve growth factor-sensitive S6 kinase in cell-free extracts from PC12 cells.
abstract: Soluble extracts from nerve growth factor (NGF)-stimulated PC12 cells prepared by alkaline lysis show a two- to 10-fold greater ability to phosphorylate the 40S ribosomal protein S6 than do extracts from control cells. The alkaline lysis method yields a preparation of much higher specific activity than does sonication. Half-maximal incorporation of 32P from [32P]ATP into S6 occurred after 4-7 min of NGF treatment. The partially purified NGF-sensitive S6 kinase has a molecular weight of 45,000. It is not inhibited by NaCl, chlorpromazine, or the specific inhibitor of cyclic AMP (cAMP)-dependent protein kinase, nor is it activated by addition of diolein plus phosphatidylserine. Trypsin treatment of either crude extracts or partially purified S6 kinase from control or NGF-treated cells was without effect. These data suggest that the S6 kinase stimulated by NGF is neither cAMP-dependent protein kinase or protein kinase C nor the result of tryptic activation of an inactive proenzyme. Treatment of intact cells with dibutyryl cAMP or 5'-N-ethylcarboxamideadenosine also increases the subsequent cell-free phosphorylation of S6. This observation suggests that cAMP-dependent protein kinase may be involved in the phosphorylation of S6 kinase.
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000201:enzymology; D000818:Animals; D002460:Cell Line; D002474:Cell-Free System / Q000187:drug effects; D009414:Nerve Growth Factors / Q000494:pharmacology*; D010673:Pheochromocytoma / Q000201:enzymology; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D019893:Ribosomal Protein S6 Kinases; D014981:Xenopus
chemical_list: D009414:Nerve Growth Factors; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D019893:Ribosomal Protein S6 Kinases