Part of a three-gene cluster containing FLC, UFC and DFC, which is coordinately regulated in response to vernalization (PubMed:15186749, PubMed:18156133). Also regulated by FLX (PubMed:15186749). SOSEKI proteins (SOK1-5) locally interpret global polarity cues and can influence cell division orientation to coordinate cell polarization relative to body axes, probably by guiding ANGUSTIFOLIA (AN) polarized localization (PubMed:30737509, PubMed:32004461). Homodimer (PubMed:30737509). Forms long polymer filaments with other SOKs proteins polymers (e.g. SOK1, SOK2, SOK3 and SOK4) crucial for polar localization and biological activity (PubMed:32004461). Binds to ANGUSTIFOLIA (AN) (PubMed:32004461). SOSEKI proteins integrate apical-basal and radial organismal axes to localize to polar cell edges, pointing towards the epidermis, mainly to inner basal edges. Expressed during embryogenesis and in roots. During embryogenesis, first observed at the globular stage and accumulates in forming cotyledons at the heart stage (PubMed:30737509). Expressed in the inner basal edge of endodermal cells in the primary and lateral roots (PubMed:30737509). Epigenetically down-regulated by vernalization (PubMed:15186749, PubMed:18156133). Not regulated by SUF4 (PubMed:17138694). The DIX-like oligomerization domain is required for polymerization, edge localization and biological activity. 'Soseki' means cornerstone in Japanese. Belongs to the SOSEKI family.