Affinity grid-based cryo-EM of PKC binding to RACK1 on the ribosome

Abstract

Affinity grids (AG) are specialized EM grids that bind macromolecular complexes containing tagged proteins to obtain maximum occupancy for structural analysis through single-particle EM. In this study, utilizing AG, we show that His-tagged activated PKC βII binds to the small ribosomal subunit (40S). We reconstructed a cryo-EM map which shows that PKC βII interacts with RACK1, a seven-bladed β-propeller protein present on the 40S and binds in two different regions close to blades 3 and 4 of RACK1. This study is a first step in understanding the molecular framework of PKC βII/RACK1 interaction and its role in translation.