Phosphorylation of eIF4E
Figure 1 : GloboZymes Purified eIF4E Preparations
Typical SDS PAGE Pattern of GloboZymes Affinity-Purified Recombinant Preparation of Human eIF4E. The gel was stained with Coomassie Blue.
NOTE: In addition to wild type eIF4E, GloboZymes provides several phosphorylation and other site-directed mutants of this initiation factor including eIF4E(S209A), eIF4E(T210A), eIF4E(S209AT210A), eIF4E(S53A), eIF4E(S124A).
Figure 2: GloboZymes Anti-eIF4E
Extract of bovine kidney (30 ug) was subjected to Western Blotting with GloboZymes Anti-eIF4E. This antiserum was produced in rabbits to affinity-purified recombinant eIF4E protein extracted following SDS-PAGE electrophoresis of the preprations. Western blotting with preimmune serum showed no reaction.
Figure 3: Signaling Pathways Regulating eIF4E Phosphorylation – GloboZymes cPK
GloboZymes provides purified preparations of insulin-stimulated cPK from bovine kidney. These preparations phosphorylate eIF4E at Ser209 and Thr210. Interestingly, Thr210 is rapidly and preferentially dephosphorylated by PP2A which may be one reason this phosphorylation has not been detected in cell cultures. PP2A may thus, at least in part, confer the site specificity of eIF4E phosphorylation at Ser209 in response to mitogenic stimuli.
eIF4E and Fragile X Mental Retardation Protein
Fragile X mental retardation protein (FMRP) acts to regulate translation of specific mRNAs through its binding of eIF4E via CYFIP1. This binding of eIF4E occurs at a domain on CYFIP1 that is structurally similar to those present in 4EBPs. The FMRP/CYFIP1/eIF4E complex prevents the eIF4E-eIF4G interaction, which is necessary for translation to occur. The FMRP/CYFIP1/eIF4E interaction is strengthened by the presence of mRNA(s). In particular, BC1 RNA, which is a non-translatable dendritic mRNA, allows for an optimal interaction between FMRP and CYFIP1 and specific mRNAs with the FMRP/CYFIP1/eIF4E complex at synapses. Dissociation of eIF4E from CYFIP1 occurs in response to increased synaptic stimulation of neurons, which then allows for the eIF4E-eIF4G interaction to occur and hence the initiation of translation.