E3 ubiquitin-protein ligase that regulates the degree of methylesterification of pectin in seed mucilage. May be involved in the recycling of pectin methylesterase enzymes in the endomembrane system of seed coat epidermal cells. Possesses E3 ubiquitin-protein ligase activity in vitro when associated with the E1 enzyme UBA1 and the E2 enzyme UBC8. May be involved in xylem development. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Highly expressed in stems. Expressed in root xylem and seed coat. The RING-type zinc finger domain is required for E3 ligase activity. Seed coat mutant displaying primary wall detachment, reduced mucilage extrusion, and increased mucilage adherence. Decreased degree of homogalacturonan methylesterification in seed mucilage.