# Identification of Aspartyl-tRNA Synthetase as Co-purifying with Wheat Germ eIF2

## TL;DR

A long-unknown protein that consistently co-purified with wheat germ eIF2 was identified as aspartyl-tRNA synthetase, which may link translation and stress responses.

## Contribution

Identification of aspartyl-tRNA synthetase as a co-purifying protein with wheat germ eIF2 using archived samples and mass spectrometry.

## Key findings

- The co-purifying ~61kDa protein was identified as aspartyl-tRNA synthetase.
- Aspartyl-tRNA synthetase may form stable complexes linking translation initiation and stress responses.
- The protein serves as a receptor for the R enantiomer of β-aminobutyric acid.

## Abstract

Eukaryotic translation initiation factor 2 (eIF2) is among the best-studied of the translation initiation factors, but early preparations from wheat germ consistently showed a co-purifying protein of ~61kDa. As this protein was never identified, we revisited the question of its identity using mass spectrometry on an archived Coomassie-stained and dried gel of eIF2 purified in 1991. The co-purifying protein, aspartyl-tRNA synthetase, is notable for serving as a receptor for the R enantiomer of β-aminobutyric acid, with links to stress-induced eIF2α phosphorylation, highlighting the potential for stable “super complexes” connecting translation initiation with stress responses.