This family contains the N-terminus of Saccharomyces cerevisiae Bul1. Bul1 binds the ubiquitin ligase Rsp5, via an N terminal PPSY motif. The complex containing Bul1 and Rsp5 is involved in intracellular trafficking of the general amino acid permease Gap1, degradation of Rog1 in cooperation with Bul2 and GSK-3, and mitochondrial inheritance. Bul1 may contain HEAT repeats.