The effect of antibodies against Escherichia coli small ribosomal subunit proteins on protein synthesis by rat liver ribosomes.

Monovalent Fab fragments from immunoglobulins, directed against Escherichia coli small ribosomal subunit proteins, were tested for their effect on poly(U)-directed synthesis of polyphenylalanine by rat liver ribosomes. Of the 18 Fabs tested, 3, anti-S10, anti-S12, and anti-S14, inhibited polyphenylalanine synthesis; antibodies against 3 of the 21 E. coli ribosomal proteins (S1, S16, and S17) were not tested. The others were either without any appreciable effect or, as in the case of anti-S11 and anti-S18, inhibited far less. Antibodies against S12 and S14 (but not against S10) inhibited elongation factor 1-dependent binding of [14C]Phe-tRNA to rat liver 80 S ribosomes. The presumption is that the prokaryotic (E. coli) ribosomal proteins, S10, S12, and S14, possess antigenic determinants also present in eukaryotic (rat liver) ribosomal proteins; the rat liver proteins have not yet been identified.