A comparison of accessibility of ribosomal proteins on free and membrane-bound ribosomes: The ribosomal proteins potentially involved in ribosome-membrane binding

Abstract

The relative accessibility of rat liver ribosomal proteins to reductive methylation was examined using membrane-bound and free ribosomes. Comparisons indicated that 12–13 large ribosomal proteins are masked by ribosomal association with membranes. These consisted of L8, L10, L17, L26–28, L31 and L36, and probably also include L4, L5, L7 and L29. These proteins seem to surround a region centered about L3 and may partly define a ribosomal channel through which the nascent peptide emerges. Approx. 10–20% of the large ribosomal subunit surface area is shielded by the membrane.