Ubiquitin-like protein involved in thiolation of cytoplasmic tRNAs; receives sulfur from the E1-like enzyme Uba4p and transfers it to tRNA; functions as a protein tag involved in the urmylation of proteins involved in nutrient sensing and the oxidative stress response; regulates stress-dependent condensate formation, promoting phase separation of numerous proteins to promote stress resilience and survival; forms co-condensates with Uba4p resulting in increased target urmylation