Beta subunit of the SNF1 kinase complex, which is required for transcriptional, metabolic, and developmental adaptations in response to glucose limitation. Has a structural role, mediating heterotrimer formation, and a regulatory role, defining carbon source-regulated subcellular location and substrate specificity of the SNF1 kinase complex. Promotes the PKA-regulated relocalization of the SNF1 kinase complex to the vacuolar membrane in response to various types of carbon stress. Component of the SNF1 kinase complex, a heterotrimeric complex composed of the catalytic alpha subunit SNF1, one of the three related beta subunits SIP1, SIP2 or GAL83, and the regulatory gamma subunit SNF4. The beta subunit serves as a bridge between the catalytic and the regulatory subunit. Interacts (via KIS domain) with SNF1. Interacts (via ASC domain) with SNF4. Resides in the cytosol during growth in glucose and relocalizes to the vacuolar membrane in response to carbon stress. Phosphorylated by SNF1 in vitro. Present with 623 molecules/cell in log phase SD medium. Belongs to the 5'-AMP-activated protein kinase beta subunit family.