Identification of a rapidly dephosphorylating 95-kDa protein as elongation factor 2 during 8-Br-cAMP treatment of N1E115 neuroblastoma cells.
Treatment of 8-Br-cAMP promotes neurite outgrowth and neuronal differentiation in N1E115 mouse neuroblastoma cells. Prior or simultaneous treatment of PMA blocks 8-Br-cAMP-mediated neurite outgrowth. Phosphorylation of cellular proteins during these treatments was examined in a permeabilized cell system. While PMA promotes phosphorylation of the heat-stable protein kinase C substrates MARCKS and neuromodulin, 8-Br-cAMP hastens the dephosphorylation of a protein of M(r)95k (p95). Extensively purified, N-terminal sequenced, and judged from its phosphorylation properties, p95 was identified as the eukaryotic elongation factor-2 (eEF-2), whose dephosphorylation has been reported to be related to an increase in protein synthesis. It is likely 8-Br-cAMP stimulates dephosphorylation of eEf-2, promotes protein synthesis that eventually leads to neuronal differentiation in N1E115 cells.
Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D009419:Nerve Tissue Proteins; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D010750:Phosphoproteins; D015124:8-Bromo Cyclic Adenosine Monophosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate