Fig. 1. IFE-1 and PGL-1 proteins interact directly in vitro. [³⁵S]IFE proteins were tested for binding to GST-PGL-1. Bound proteins were analyzed by SDS-PAGE on 12% gels. The input lanes contain 10% of the amount of radiolabeled protein used in the binding assays. The identity of the upper band in the IFE-1 input lane, which is also present in other IFE input lanes, is not known. (A) [³⁵S]IFE proteins were tested for binding to GST-PGL-1 or GST as indicated. (B) [³⁵S]IFE-1 was treated with RNase A or water, before incubating with GST-PGL-1. The slight variation in intensity of the [³⁵S]IFE-1 band in the ‘+’ and ‘-’ lanes was not observed in a duplicate experiment. The Ethidium Bromide-stained agarose gel of RNA extracted after RNase A treatment or mock treatment shows that endogenous RNAs were reduced to below detection by RNase A treatment.