This is the C2H2 zinc finger domain found in E3 ubiquitin ligase Hakai. Hakai targets tyrosine-phosphorylated E-cadherin [1]. It carries a Tyr(P)-binding domain, coined the HYB domain for Hakai phosphotyrosine (Tyr(P)) binding. HYB domain structure illustrates that it forms a zinc-coordinated homodimer in an antiparallel, intertwined configuration, utilizing residues from the Tyr(P)-binding region of two Hakai monomers. The C-terminal region of the HYB domain, which harbors the atypical zinc-coordination motif and key residues involved in the Tyr(P) interaction, plays an important role in the dimerization observed in the HYB domain [2].

1: Structure of a novel phosphotyrosine-binding domain in Hakai that targets E-cadherin. Mukherjee M, Chow SY, Yusoff P, Seetharaman J, Ng C, Sinniah S, Koh XW, Asgar NF, Li D, Yim D, Jackson RA, Yew J, Qian J, Iyu A, Lim YP, Zhou X, Sze SK, Guy GR, Sivaraman J; EMBO J. 2012;31:1308-1319. PMID:22252131

2: Dimeric switch of Hakai-truncated monomers during substrate recognition: insights from solution studies and NMR structure. Mukherjee M, Jing-Song F, Ramachandran S, Guy GR, Sivaraman J; J Biol Chem. 2014;289:25611-25623. PMID:25074933