Component of the U5 snRNP complex required for pre-mRNA splicing. Binds GTP. Belongs to the CWC complex (or CEF1-associated complex), a spliceosome sub-complex reminiscent of a late-stage spliceosome 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. Component of the U4/U6-U5 tri-snRNP complex composed of the U4, U6 and U5 snRNAs and at least PRP3, PRP4, PRP6, PRP8, PRP18, PRP31, PRP38, SNU13, SNU23, SNU66, SNU114, SPP381, SMB1, SMD1, SMD2, SMD3, SMX2, SMX3, LSM2, LSM3, LSM4, LSM5, LSM6, LSM7, LSM8, BRR2 and DIB1. Interacts (via C-terminus) with CWC21. Interacts (via N-terminus) with PRP8 (via SCwid domain). Present with 300 molecules/cell in log phase SD medium. Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. EF-G/EF-2 subfamily.