This entry includes E3 ubiquitin-protein ligase APD1 to 4 from Arabidopsis. They are involved in pollen mitosis II (PMII) regulation during male gametogenesis [1]. This entry represents a functionally uncharacterised domain found in the middle of APD1-4 and in uncharacterised sequences mainly from arthropods. There are two completely conserved C residues that may be functionally important.

1: Four closely-related RING-type E3 ligases, APD1-4, are involved in pollen mitosis II regulation in Arabidopsis. Luo G, Gu H, Liu J, Qu LJ; J Integr Plant Biol. 2012;54:814-827. PMID:22897245