Transcription activator that binds to 5'-TATCCA-3' elements in gene promoters. Derepresses strongly the sugar-repressed transcription of promoters containing SRS or 5'-TATCCA-3' elements. Functions with GAMYB to integrate diverse nutrient starvation and gibberellin (GA) signaling pathways during germination of grains. Sugar, nitrogen and phosphate starvation signals converge and interconnect with GA to promote the co-nuclear import of MYBS1 and GAMYB, resulting in the expression of a large set of GA-inducible hydrolases, transporters, and regulators that are essential for mobilization of nutrient reserves in the endosperm to support seedling growth (PubMed:22773748). Homodimer (PubMed:12172034). Interacts with GAMYB (PubMed:22773748). Preferentially localized to the nucleus under sugar starvation conditions. Glucose inhibits nuclear localization. Expressed in aboveground tissues, with the highest level in leaves. Repressed by sucrose and gibberellic acid (GA).