Overview:

The translational repressor protein 4EBP1 interacts directly with eukaryotic translation initiation factor 4E (EIF4E). This interaction inhibits the formation of the multi-subunit complex that recruits 40S ribosomal subunits to the 5' end of mRNAs thus preventing cap-dependent translation. Hyperphosphorylation of 4EBP1 disrupts its binding with EIF4E (1). Treating adipose cells with insulin leads to increased 4EBP1 phosphorylation (1). 4EBP1 is expressed in most tissues, with high levels detected in adipose tissue, pancreas and skeletal muscle (2). 4EBP1 is phosphorylated at several residues including Thr45 in response to the phorbol ester TPA.

References:

1. Pause, A. et al: Insulin-dependent stimulation of protein synthesis by phosphorylation of a regulator of 5-prime-cap function. Nature371: 762-767, 1994.
,br>2. Tsukiyama-Kohara, K. et al: Tissue distribution, genomic structure, and chromosome mapping of mouse and human eukaryotic initiation factor 4E-binding proteins 1 and 2. Genomics38: 353-363, 1996.