(A) Plasmids expressing HA-tagged forms of the yeast proteins LDB17, EAP1, VRP1 or eIF1A under the control of the yeast GAL1 promoter were introduced into isogenic strains expressing wild-type eIF5A or eIF5A-S149P. Cells were grown at semi-permissive 33°C in galactose medium, broken with glass beads in the presence of 10% trichloroacetic acid (TCA), and two different amounts of each extract differing by a factor of 2 were loaded in successive lanes and subject to immunoblot analysis using monoclonal anti-HA or polyclonal anti-yeast eIF2α antiserum.
(B) The experiment in panel A was repeated using an LDB17 construct in which Ala codons were substituted for the nine Pro codons in the polyproline motif.