IMPACT, a mammalian homolog of yeast YIH1, competes with EIF2AK4 (GCN2) for binding to GCN1, which is required for activation of EIF2AK4 and may act by transferring unacylated tRNAs from the ribosome to EIF2AK4 (inferred from mouse homologs). IMPACT thereby inhibits phosphorylation of EIF2A by EIF2AK4 in response to amino acid deficiency (inferred from mouse homologs). IMPACT is preferentially expressed in neurons, associates with translating ribosomes, enhances translation initiation, and promotes neuritogenesis (inferred from mouse homologs).
