This family consists of the N-terminus and thus the z-alpha domain of double-stranded RNA-specific adenosine deaminase (ADAR), an RNA- editing enzyme. The z-alpha domain is a Z-DNA binding domain, and binding of this region to B-DNA has been shown to be disfavoured by steric hindrance [1].

1: The solution structure of the Zalpha domain of the human RNA editing enzyme ADAR1 reveals a prepositioned binding surface for Z-DNA. Schade M, Turner CJ, Kuhne R, Schmieder P, Lowenhaupt K, Herbert A, Rich A, Oschkinat H; Proc Natl Acad Sci U S A 1999;96:12465-12470. PMID:10535945