May be involved in pre-mRNA splicing. Belongs to the CWC complex (or CEF1-associated complex), a spliceosome subcomplex composed of the U2, U5 and U6 snRNAs and at least BUD13, BUD31, BRR2, CDC40, CEF1, CLF1, CUS1, CWC2, CWC15, CWC21, CWC22, CWC23, CWC24, CWC25, CWC27, ECM2, HSH155, IST3, ISY1, LEA1, MSL1, NTC20, PRP8, PRP9, PRP11, PRP19, PRP21, PRP22, PRP45, PRP46, SLU7, SMB1, SMD1, SMD2, SMD3, SMX2, SMX3, SNT309, SNU114, SPP2, SYF1, SYF2, RSE1 and YJU2. Present with 3260 molecules/cell in log phase SD medium. Belongs to the CWC22 family.