Particulate aminoacyl-tRNA synthetases are retained on heparin bound to Sepharose

Fractions of reticulocyte lysates were retained on heparin immobilized on Sepharose 4B and further separated by gel filtration on Sepharose 6B. These fractions contain aminoacyl-tRNA synthetases for 12 amino acids tested. Most synthetases with the highest specific activity are present in the fraction of approximately 40S. Particulate synthetases present in the postmicrosomal pellet of rat liver and synthetases associated with polyribosomes are almost completely adsorbed on heparin-Sepharose but free enzymes in the cytosol are not retained. Since only particulate synthetases are retained on the affinity carrier, their adsorption may be due to the presence of protein-synthesis factors, in particular peptide initiation and elongation factors, in the complexes of synthetases.