Subunit of the NTC(Nineteen)/Prp19 complex, which is part of the spliceosome (PubMed:24755291, PubMed:28087625). The complex participates in spliceosome assembly, its remodeling and is required for efficient spliceosome activation (PubMed:24755291, PubMed:28087625). Essential for efficient pre-mRNA splicing (PubMed:24755291, PubMed:28087625). In embryos, efficient pre-mRNA splicing of zygotic transcripts is essential during dynamic cellular processes that require rapid division and/or dramatic changes in gene expression such as blastoderm cellularization, tracheal branching morphogenesis, Malpighian morphogenesis and epidermal development (PubMed:24755291, PubMed:28087625, PubMed:10502111). Part of its role in promoting embryo tracheal development is also due to specifically splicing bnl transcripts which results in the activation of the BNL-FGF pathway (PubMed:28087625). Component of the NTC(Nineteen)/Prp19 complex composed of at least fand, Prp19,CG9667/ISY1 and Cdc5/CDC5L. Within the complex, interacts with Prp19 and ISY1/CG9667. Expressed in adult ovaries and 0-3 hours embryos (at protein level). Named 'fandango' after the Iberian folk dance to highlight the similarity of the blastoderm cellularization phenotype to the charleston/kuk phenotype (PubMed:24755291). The phenotype 'faint sausage (fas)', consisting of a poorly differentiated cuticle and head, was previously associated with the immunoglobulin domain protein CG17716 but is now known to be caused by mutations in the protein 'fandango' (PubMed:24755291). Belongs to the crooked-neck family.