ligase in budding yeast. We have identified the BUL2 gene as a functional homologue of
BUL1. The bul1 bul2 double disruptant was sensitive to various stresses, such as high
temperature, salts, and a non-fermentable carbon source. Each Bul protein has a putative
PY-motif that has been predicted to interact with one of three WW-domains of Rsp5. A
mutant Bul1 containing an altered PY-motif was defective in ability to bind to Rsp5 in the two …