UniProtKB description: Ribosome preservation factor that protect a small pool of nontranslating, vacant ribosomes in cells under nutrient starvation conditions. Under nutrient-limiting conditions, cells reduce ribosome biogenesis and degrade ribosomes via autophagy (ribophagy) or proteasomal degradation. To avoid excessive degradation during starvation, STM1 binds to and protects 80S ribosomes from proteasomal degradation. Under nutrient-sufficient conditions, TORC1 phosphorylates and inhibits STM1 to prevent formation of dormant 80S ribosomes (PubMed:16580682, PubMed:19666721, PubMed:21460238, PubMed:23206692, PubMed:34769086, PubMed:36691768). Acts as an inhibitor of mRNA translation by promoting ribosome hibernation: clamps the two ribosomal subunits, thereby preventing their dissociation, and inhibits translation by excluding mRNA-binding (PubMed:19666721, PubMed:21460238, PubMed:29069440, PubMed:36691768, PubMed:22096102). Acts via its association with eEF2 (EFT1), promoting ribosome stabilization and storage in an inactive state (PubMed:23206692, PubMed:29069440). May also repress translation by preventing association of eEF3 (YEF3 and HEF3) with ribosomes (PubMed:19666721). Binds specifically G4 quadruplex (these are four-stranded right-handed helices, stabilized by guanine base quartets) and purine motif triplex (characterized by a third, antiparallel purine-rich DNA strand located within the major groove of a homopurine stretch of duplex DNA) nucleic acid structures. These structures may be present at telomeres or in rRNAs (PubMed:15044472). Acts with CDC13 to control telomere length homeostasis (PubMed:15044472). Involved in the control of the apoptosis-like cell death (PubMed:15044472).