Accessibility of Ribosomal Proteins to Lactoperoxidase‐Catalyzed Iodination Following Phosphorylation and During Subunit Interaction

Abstract

Lactoperoxidase-catalyzed iodination was employed as a probe to monitor conformational change in 40-S ribosomal subunits from rat liver. Phosphorylation of protein S6 resulted in no detectable change in the iodination pattern of 40-S subunit proteins. The conformation of the small subunit apparently remains unaltered following phosphorylation. The differences noted in the iodination pattern between 40-S ribosomal proteins derived from isolated subunits and those from 80-S monosomes suggest that the 40-S subunit undergoes a conformational change during association with the 60-S subunit. Following 40-S and 60-S subunit association, proteins S2, S3, S5, S6, S8, S10 and S14 became less accessible to iodination. These proteins may be located at the interface between the 40-S and 60-S subunits.