Responsible for the proper stability and function of septins during cytokinesis. Required for the correct formation of the medial septin ring structure in mitosis and for the proper localization of endo-glucanases agn1 and eng1, which are needed for efficient cell separation. May act as a landmark for the localization of hydrolytic proteins to the medial region. Localizes to the medial ring at the cell cortex of dividing cells (PubMed:12654901). Initially forms a single ring, which subsequently splits into two distinct rings as the septum forms, and disappears as cells separate (PubMed:12654901). Requires septins for proper localization (PubMed:12654901). Cell cycle-regulated with a peak during septation (at protein level). Induced by transcription factor ace2 during mitosis. Degraded via SCF-dependent proteolysis. Belongs to the BUD4 family.