In vitro binding assay indicates that eIF3-p44 binds to 4.1R.

The eIF3-p44 cDNA was subcloned into the pGEX-2T vector and expressed as a GST/eIF3-p44 fusion protein in Escherichia coli. (A) Purified GST (lane 2) and GST/eIF3-p44 fusion protein (lane 3) were visualized by Coomassie blue staining. (B) Binding of GST/eIF3-p44 to 4.1R-80 (80-kd isoform) in vitro.³⁵S-methionine–labeled 4.1R-80 (lane 1) was incubated with affinity-purified GST (lane 2) or GST/eIF3-p44 fusion protein (lane 3) previously coupled to glutathione–agarose beads. After incubation, the bound complexes were analyzed by SDS-PAGE and autoradiography. Radiolabeled 4.1R-80 bound to GST/eIF3-p44 fusion protein (lane 3) but not GST alone (lane 2).