Translational regulator that ensures constant high levels of translation under amino acid starvation. Plays a role as a negative regulator of the GCN2 kinase activity; impairs GCN1-mediated GCN2 activation, and hence GCN2-mediated eIF-2-alpha phosphorylation in amino acid-starved cells and subsequent down-regulation of protein synthesis (PubMed:15126500, PubMed:15937339, PubMed:24333428). In normal conditions, it resides in a actin complex and has no activity (PubMed:15126500). Interacts (via N-terminus) with GCN1 (via C-terminus); this interaction reduces the GCN1-GCN20 complex formation and prevents the interaction of GCN1 with GCN2 protein kinase and GCN2 activation in amino acid-starved cells (PubMed:15126500, PubMed:21239490). Interacts (via C-terminus) with ACT1; this interaction occurs in a GCN1-independent manner (PubMed:15126500, PubMed:21239490). Interacts with RPL39; this interaction occurs in a GCN1-independent manner (PubMed:22404850). Associates (via middle region) with ribosomes; this association occurs in a GCN1-independent manner and persists under amino acid starvation conditions (PubMed:22404850). Present with 3030 molecules/cell in log phase SD medium. Belongs to the IMPACT family.