Fig. 4.

Co-immunoprecipitation of epitope-tagged and endogenous human GPX1 transcripts bound to NSEP1. mRNA from Saos-2 cells was analyzed as described in the legend to Figure 1. RT-PCR products were detected by ethidium bromide staining of agarose gels. The upper part shows the products amplified by PCR primers directed to the epitope-tagged transcripts (“GPx1-HA”); the lower part, to endogenous transcripts (“GPx1”). Lane 1: no-RT control; Lane 2: total cellular RNA; Lane 3: co-immunoprecipitated RNA from cells transfected with a construct containing the SECIS element; Lane 4: co-immunopreci-pitated RNA from cells transfected with a construct with the distal stem and loop of the SECIS element deleted (as indicated by light shading in Fig. 2).