Localization Of Glutamyl/Prolyl-Trna Synthetase Within The Eukaryotic Multienzyme Complex By Immunoelectron Microscopy

Abstract

Aminoacyl-tRNA synthetases are the family of enzymes responsible for correctly linking tRNA molecules with amino acids so that the latter may be subsequently incorporated into growing polypeptide chains. A unique feature of aminoacyl-tRNA synthetases from higher eukaryotes is the existence of a high molecular mass multisynthetase complex. This approximately 1 × 106Da particle measures approximately 27 nm in diameter and appears to be a cup or elongated “U“ shape as suggested by distinct orientations visible in negatively stained electron micrographs. A working model of the structure has been proposed which divides the particle into three domains. The composition of each domain as well as relative positions of individual polypeptides within each have been proposed, but to date there has been no precise localization of any specific component or site within the multisynthetase complex. This study describes the first localization of a particular polypeptide within the particle.