Candidate protein interactors of sexually dimorphic on the Y chromosome (SdY) in Atlantic salmon

Atlantic salmon depend on genetic cues to determine whether an individual is male or female. A novel sex-determining gene, sexually dimorphic on the Y chromosome (sdY), is found exclusively in all salmonids. Unlike other sex-determining genes, sdY lacks a DNA-binding domain. Instead, it is a divergent, truncated form of interferon regulatory factor 9. As a recently discovered gene, little is known about sdY; how it is involved in sex-determination and what proteins interact with it. Identification of protein interactors was done through a variety of techniques including yeast two-hybridization, co-immunoprecipitation and histidine-tagged pull down assays. These assays identified several proteins: SdY itself, 40S ribosomal protein S16 and SA, isocitrate dehydrogenase, heat shock protein HSP 90-beta, and ras GTPase-activating-like protein IQGAP1, as well as creatine kinase, GDP-mannose-4,6-dehydratase, sodium/potassium-transporting ATPase subunit alpha-1, AP-1 complex subunit beta-1, and hydroxysteroid dehydrogenase (17-beta) 4. The yeast two-hybrid assay also identified 3’ UTR of annexin A7-like and transmembrane protein 91-like, most likely false positives. This broad range of candidates has led me to believe that SdY is involved either in the biosynthesis of testosterone or in the testosterone signalling pathway.