DNA-binding adapter subunit of the SEU-LUG transcriptional corepressor of the C class floral homeotic gene AGAMOUS during the early stages of floral meristem development. Is part of the A class cadastral complex that define the boundaries between the A and C class homeotic genes expression and function. Interacts together with APETALA2 and LEUNIG to repress AGAMOUS expression. In association with LUG, regulates petal shape through AGAMOUS-independent mechanisms. Controls cell division during petal development and enable the proper patterning of petal blade vasculature. Required for the proper elaboration of petal polarity along the adaxial/abaxial axis. May act through direct or indirect regulation of PHABULOSA and YAB1 and thus regulate cellular proliferation within the developing petal blade. In association with AINTEGUMENTA (ANT), coordinates patterning cues and cellular proliferation along the three positional axes of the developing gynoecium. Required for the development of the medial ridge and subsequent ovule initiation. Forms a corepressor complex with LUG; LUG is the transcription repressor subunit and SEU the specific DNA-binding adapter. Interacts with AGL24-AP1 and SVP-AP1 dimers when complexed to SEU. Interacts with AP1/AGL7 and SEP3/AGL9 (PubMed:15277686, PubMed:16679456, PubMed:16854969). Binds to LUH (PubMed:18390806). Does not localize in the nucleolus. Expressed in root, leaves, seedlings, vegetative and reproductive shoot apical meristems, seeds, floral meristems and all floral organs. Induced by exposures to biotic stress (e.g. nematode and Botrytis cinerea) and abiotic stress (e.g. salt, genotoxic, wounding, drought and oxidative stress). Repressed by exposures to biotic stress (e.g. Agrobacterium tumefaciens) and abiotic stress (e.g. hypoxia, cycloheximide, 2,4-dichlorophenoxyacetic acid, AgNO(3) and aminoethoxyvinylglycine). Contains a dimerization domain which shares similarity with the LIM-binding domain of animal transcription coregulators. Ectopic and precocious expression of AGAMOUS, leading to partial homeotic transformation of the external floral organs. Belongs to the adn1/SEU family.