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.
Li
H
H
Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Chen
H C
HC
Huang
F L
FL
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