Enables chromatin binding activity. Acts upstream of or within anterior/posterior pattern specification; blastocyst formation; and mRNA splicing, via spliceosome. Located in chromatin and nuclear matrix. Part of U2 snRNP. Is expressed in several structures, including central nervous system; endocrine gland; genitourinary system; hemolymphoid system gland; and sensory organ. Human ortholog(s) of this gene implicated in hepatocellular carcinoma and myelodysplastic syndrome. Orthologous to human SF3B1 (splicing factor 3b subunit 1). [provided by Alliance of Genome Resources, Apr 2022]