May negatively regulate the SNF1 kinase by promoting the interaction of the REG1/GLC7 phosphatase complex with the kinase. Deletion of SIP5 promotes resistance to artimisin, which is probably an indirect effect of an action on the electron transport chain. Interacts with NPA1, SNF1 and REG1. Present with 556 molecules/cell in log phase SD medium. Belongs to the SIP5 family.