Acts as a stomatal lineage scaffold which regulates subcellular localization and transient polarization of kinases (e.g. ASK7/BIN2 and ASK3/SK12) involved in asymmetric cell division (ACD) in a BASL-dependent manner. Localized throughout the plasma membrane in asymmetric cell division (ACD) precursors (By similarity). Transient polar localization and segregation unevenly (distal to the newly divided meristemoid and parallel to the division plane) during meristemoid asymmetric divisions in a BASL-dependent manner (By similarity). Present in the cytoplasm of meristemoids and cell periphery in stomatal lineage ground cells (SLGCs), in a polarized pattern (By similarity). Decreased accumulation of ASK7/BIN2 at the plasma membrane and impaired polarization of ASK7/BIN2 in asymmetric cell division (ACD) precursors thus leading to its nuclear localization in the meristemoids. Truncated N-terminus. Truncated N-terminus.