This domain is found to the N-terminus of the SET domain in the EZH2 protein [1]. It is a zinc binding domain.

1: Structure of the catalytic domain of EZH2 reveals conformational plasticity in cofactor and substrate binding sites and explains oncogenic mutations. Wu H, Zeng H, Dong A, Li F, He H, Senisterra G, Seitova A, Duan S, Brown PJ, Vedadi M, Arrowsmith CH, Schapira M; PLoS One. 2013;8:e83737. PMID:24367611