Protein that facilitates co-transcriptional histone H2B ubiquitination; scaffold protein that promotes oligomerization of E3 ligase Bre1p; contains an intrinsically disordered region that phase separates, to form a core encapsulated by Bre1p that recruits Ub-conjugating enzyme Rad6p, elevating catalytic activity along gene bodies; null mutant forms abnormally large cells, and homozygous null mutant displays delayed premeiotic DNA synthesis and reduced efficiency of meiotic nuclear division