The B regulatory subunit may modulate substrate selectivity and catalytic activity, and also may direct the localization of the catalytic enzyme to a particular subcellular compartment. PP2A consists of a common heteromeric enzyme, composed of a catalytic subunit (subunits C), a constant regulatory subunit (subunit A), and a variety of regulatory subunits such as subunits B (the R2/B/PR55/B55, R3/B''/PR72/PR130/PR59 and R5/B'/B56 families) (By similarity). Interacts with SIC/RON3 (PubMed:26888284). Expressed ubiquitously. May be due to a competing donor splice site. Belongs to the phosphatase 2A regulatory subunit B family.