Structure and Function of the Escherichia coli Ribosome: Immunochemical Analysis

Abstract

INTRODUCTION
The availability of specific antibodies has proven extremely useful in analyses of the structure and function of enzymes (Arnon 1971; Margoliash, Reichlin and Nisonoff 1967; Landsteiner 1945; Benjamini, Michaeli and Young 1972). The essential understanding of the nature of the antigenic determinants came from studies of the immunogenicity of synthetic copolymers of amino acids and from parallel studies with proteins of known primary sequences. The information that emerged was that antibodies can be directed against either amino acid sequences or against protein conformation and that the minimal immunogenic sequence was four contiguous amino acids, although as many as ten amino acids might be required to bind the antibody (Sela 1966Sela 1969; Sela et al. 1967; Benjamini, Michaeli and Young 1972).

It occurred to me seven or eight years ago that the same immunochemical methods that had been used to explore the structure of enzymes might well be applied to more complex assemblies and perhaps even to organelles. For this reason I began to raise antibodies against Escherichia coli ribosomes, ribosomal subunits and then, as they became available, against each of the 55 individual ribosomal proteins. The purpose of this article is to summarize the results, to show the contribution the immunochemical experiments have made to knowledge of the structure and function of bacterial ribosomes, and finally, to indicate possible further applications of this approach.

The earliest experiments were with antibodies against intact 70S ribosomes (Quash et al. 1962). Estrup and Santer (1966) immunized rabbits with E. coli 30S and...