Unknown. In males lacking the Y chromosome, its strong overexpression leads to the appearance of proteinaceous star-shaped crystals in the primary spermatocytes causing meiotic drive, possibly by interfering with normal casein kinase 2 activity. Interacts in vitro with the casein kinase 2 alpha subunit (CkII-alpha). The relevance of such interaction is however unclear in vivo. Probably not expressed in wild-type flies. In males lacking the Y chromosome, it is testis-specific and constitutes the main component of star-shaped crystals. In wild-type flies, it is strongly down-regulated by double-stranded RNA (dsRNA) interference mediated by Su(Ste) transcripts. In males lacking the Y chromosome, the absence of Su(Ste) locus, relieves such down-regulation, explaining why it is strongly expressed. There are multiple copies of the stellate gene in fruit fly, encoding proteins that are extremely similar, which makes their individual characterization difficult. Thus, most experiments probably do not discriminate between the different members. Belongs to the casein kinase 2 subunit beta family.