Linked Life Data

8662663

Source:http://linkedlifedata.com/resource/pubmed/id/8662663

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
20
pubmed:dateCreated
1996-8-29
pubmed:abstractText
Translation initiation in eukaryotes is facilitated by the mRNA 5' cap structure (m7GpppX, where X is any nucleotide) that binds the multisubunit initiation factor eIF4F through one of its subunits, eIF4E. eIF4E is a phosphoprotein whose phosphorylation state positively correlates with cell growth. Protein kinase C phosphorylates eIF4E in vitro, and possibly in vivo. Using recombinant eIF4E incubated in vitro with purified protein kinase C and analyzed by solid-phase phosphopeptide sequencing in combination with high performance liquid chromatography coupled to mass spectrometry, we demonstrated that the third amino acid of the peptide SGSTTK (Ser209) is the major site of phosphorylation. This finding is consistent with the newly assigned in vivo phosphorylation site of eIF4E (Joshi, B., Cai, A. L., Keiper, B. D., Minich, W. B., Mendez, R., Beach, C. M., Stepinski, J., Stolarski, R., Darzynkiewicz, E., and Rhoads, R. E. (1995) J. Biol. Chem. 270, 14597-14603). A S209A mutation resulted in dramatically reduced phosphorylation, both in vitro and in vivo. Furthermore, the mutant protein was phosphorylated on threonine (most probably threonine 210) in vivo. Here we show that in the presence of the recently characterized translational repressors 4E-BP1 or 4E-BP2, phosphorylation of eIF4E by protein kinase C is strongly reduced. This suggests a two-step model for the phosphorylation (and activation) of eIF4E by growth factors and hormones: first, dissociation of eIF4E from 4E-BPs, followed by eIF4E phosphorylation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
17
pubmed:volume
271
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11831-7
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Phosphorylation of eIF-4E on serine 209 by protein kinase C is inhibited by the translational repressors, 4E-binding proteins.
pubmed:affiliation
Department of Biochemistry and McGill Cancer Centre, McGill University, Montreal, Quebec, Canada.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't