eIF-2 kinases: regulators of general and gene-specific translation initiation

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Phosphorylation of eukaryotic initiation factor-2 (eIF-2) is a key regulator of translation initiation in eukaryotes.
• Two mammalian eIF-2 kinases, double-stranded-RNA-dependent kinase (PKR) and heme-regulated inhibitor kinase (HRI), share distinct structural features with each other but not other kinases.
• Yeast studies reveal GCN2, a related kinase, also phosphorylates eIF-2.

Purpose of the Study:

• To present current models for the regulation of mammalian eIF-2 kinases (PKR and HRI) and yeast GCN2.
• To discuss the molecular mechanisms by which eIF-2 kinase regulation controls gene-specific translation, contrasting with general translation control.

Main Methods:

• Sequence analysis of mammalian eIF-2 kinases (PKR and HRI).
• Review of existing literature on yeast GCN2 function and regulation.
• Comparative analysis of kinase structures and regulatory pathways.

Main Results:

• PKR and HRI are structurally related mammalian eIF-2 kinases involved in general translation control.
• GCN2, a yeast homolog, phosphorylates eIF-2 but regulates gene-specific translation.
• Distinct regulatory models exist for PKR, HRI, and GCN2.

Conclusions:

• The eIF-2 phosphorylation system exhibits both conserved and divergent regulatory strategies across species.
• Understanding these kinase pathways provides insights into how general translation control is adapted for specific gene expression.