A Immunoblot analysis of immunoprecipitated Flag-tagged histone H2B with anti-Flag (bottom panel) or anti-SUMO (upper panel) antibodies in WT, ulp2Δ, SUMO-all KR or ulp2Δ SUMO-all KR strains carrying empty vector or pRS426-FLAG-HTB1. One, two or three asterisks represent mono, di and polysumoylated histones, respectively. Note that the apparent diSUMO-H2B species (**) in ulp2Δ SUMO-all KR cells migrates more slowly than H2B linked to a SUMO dimer, suggesting that this species likely represents a low level of H2B with SUMO attached to two different histone lysines (lane 8; also see weaker band in lane 6). 