Source: Recombinant human produced in E. coli

Purity: > 90% by SDS-PAGE, apparent Mr ~ 28-kDa

Supplied: In 50 μl of 50 mM Tris-HCl pH 7.0 buffer containing 14 mM β-mercaptoethanol, 1 mM benzamidine, 0.1 mM phenylmethanesulfonyl fluoride, 1 mM EDTA and 10% glycerol. Maintain in aliquots at -70° C. Avoid repeated thawing.

Synonyms: Eukaryotic Protein Synthesis Initiation Factor 4E Serine 124 to Alanine Mutant; eI-F4ES124A.


Background: The mRNA Cap-binding protein synthesis initiation factor 4E (eIF4E) participates in an early rate limiting step in protein synthesis. Over-expression of eIF4E leads to cell transformation and tumorigenesis and occurs in a number of cancer cells. In quiescent cells, eIF4E occurs as an inactive complex with the 4EBP binding proteins. In response to insulin and other extracellular stimuli, eIF4E dissociates from 4EBP and is recruited to the active eIF4F complex. The active eIF4F complex contains eIF4A and eIF4G in addition to eIF4E.  In response to insulin and other growth factors, eIF4E is phosphorylated at Ser209. This phosphorylation enhances the affinity of eIF4E to capped mRNA. It is catalyzed by the Mitogen-Activated Protein Kinase (MAPK) Interacting Kinases (Mnk’s). It is also catalyzed by an insulin-stimulated kinase termed cPK which also phosphorylates Thr210 on the initiation factor.  Preparations of eIF4ES124A undergo phosphorylation at Ser209 and Thr210 and may be useful as control in studies to examine the phosphorylation and function of the native protein.

Figure: SDS-PAGE pattern of a purified preparation of eIF4E(S124A). The gel was stained with Coomassie Blue.

ReferencesJ Biol Chem 270, 14824-14828;  J Biol Chem 270, 14597-14603Biochime 76, 822-830;  J Biol Chem 271, 11831-11837;  J Biol Chem 270, 21684-21688



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