Sly (Hirst et al., 2000; Costaguta et al., 2001; Zhdankina et al., 2001). However, our results with HA-tagged Gga1p and Gga2p argue that the expression levels are in fact very similar. Finally, the L203Q mutation may reduce interaction with another, unknown partner of Gga proteins that is involved in Gga function. Although we cannot rule out this possibility, the current evidence strongly favors G