The active centre of the spliceosome consists of an intricate network formed by U5, U2 and U6 snRNAs, and a pre-mRNA substrate. Prp8 is a component of the U5 snRNP that extensively crosslinks with this RNA catalytic core PMID:23354046. Structural domains comprising this superfamily share the structure of the U5-snRNA-binding domain of the pre-mRNA-processing-splicing factor 8 (Prp8). The essential spliceosomal protein Prp8 interacts with U5 and U6 snRNAs and with specific pre-mRNA sequences that participate in catalysis PMID:16431982.Due to Prp8's close association with crucial RNA sequences, together with extensive genetic evidence, it is believed that this protein directly affects the function of the catalytic core, probably acting as a splicing cofactor PMID:16431982.