Coiled Coil Domain Containing Protein 49 (CCDC49)

Cwc25 has previously been identified to associate with pre-mRNA splicing factor Cef1/Ntc85, a component of the Prp19-associated complex involved in spliceosome activation. Cwc25 is neither tightly associated with NTC nor required for spliceosome activation but is required for the first catalytic reaction. Cwc25 functions in the final step of the first catalytic reaction after the action of Prp2. Cwc25, although resistant to heat treatment, is not sufficient to replace the function of HP, indicating that another heat-resistant factor, which named HP-X, is involved. The requirement of Cwc25 and HP-X for the first catalytic reaction could be partially compensated for when the affinity-purified spliceosome was incubated in the presence of low concentrations of Mn2+.