Essential for gene silencing: has a role in the structure of silenced chromatin. May be involved in gene regulation during development. Binds RNA. The short transcript is expressed moderately during early embryonic stages (0-18 hours) but then declines in late stage embryos (15-21 hours), becoming replaced by the long transcript which persists into the adult body. Transcription utilizes two promoters. Promoter 1 gives rise to the short transcript encoding Sas10 only. Promoter 2 generates a discistronic transcript of Sas10 and Rnp4F. The longer transcript becomes an RNA duplex which is a target for RNA editing via Adar editase; Rnp4F (not Sas10) is edited. Belongs to the SAS10 family.