Characterization of the Region on Protein L7/L12 Involved in Binding to Ribosomal Particles

Abstract

Tryptic digestion of reductively methylated protein L7/L12 yields a large tryptic fragment, which comprises amino acids 1–59. At the most, two molecules of this fragment can bind to a 50‐S ribosomal particle, deprived of protein L7/L12. Besides, binding of each single 1–59 fragment competes with binding of one dimeric L7/L12 molecule. Molecular weight studies on the fragment reveal a monomeric structure. Digestion of the 1–59 fragment with carboxypeptidase Y leads to the formation of a 1–55 fragment. The binding characteristics of the latter fragment are similar to those of the 1–59 fragment. The results suggest that a monomeric stretch of L7/L12, comprising the first 55 amino acids, is sufficient for attaching L7/L12 to the ribosome. Copyright © 1982, Wiley Blackwell. All rights reserved