U6 snRNP-binding protein that functions as a recycling factor of the splicing machinery. Promotes the initial reassembly of U4 and U6 snRNPs following their ejection from the spliceosome during its maturation (PubMed:17416673). May also function as a substrate targeting factor for deubiquitinases and mediate the deubiquitination of components of the spliceosome and histones (By similarity). The egy mutant embryos that lack detectable sart3 expression display microcephaly, microphthalmia and die by 7 to 8 dpf. Pharyngeal arch formation is defective resulting in a thymus devoid of lymphocytes and exocrine pancreas development is also impaired.