U2 snRNP protein which helps to refold U2 into a structure favorable for its binding to SF3b and SF3a prior to spliceosome assembly. Mediates functional interactions between U2 RNA and PRP5. Enforces ATP dependence during formation of the prespliceosome by brokering an interaction between PRP5 and the U2 snRNP that depends on correct U2 RNA structure. Interacts with PRP11. Associates with the U2 snRNA. Present with 1360 molecules/cell in log phase SD medium. Belongs to the HTATSF1 family.