Regulates differences in leaf patterning between juvenile and mature leaves by controlling differences in the development of primordia produced during juvenile and mature phases. Acts by activating transcription of the myb-domain protein AS1, a gene involved in leaf-axis specification. Associates with the promoter and the start of the transcribed region of AS1 and up-regulates expression of AS1 through acetylation of histones H3 and H4. A number of isoforms are produced. According to EST sequences. Abundantly expressed in flowers. Weakly expressed in roots, leaves and siliques; and undetectable in 5-day-old seedlings. In the basal rosette leaves of 21-day-old plants, it is more abundant in leaves 6 and 7, which possess narrow elliptical laminae, than in leaves 1-4, which have round laminae, suggesting a possible correlation between its expression and the formation of elliptical leaf laminae in mature leaves. The NET domain could serve as an interface to localize different proteins or complexes to chromatin. Disrupted formation of elliptical leaf laminae in mature leaves.