A novel subfamily of zinc finger genes involved in embryonic development

C₂H₂ zinc finger proteins make up one of the largest protein families in eukaryotic organisms. Recent study in several different systems has identified a set of novel zinc finger proteins that appear to form a distinct subfamily that we have named the NET family. Members of the NET family (Noc, Nlz, Elbow, and Tlp-1) share two protein motifs-a buttonhead box and an Sp motif-with zinc finger proteins from the Sp family. However, the NET family is uniquely characterized by a single atypical C₂H₂ zinc finger, in contrast to the Sp family that contains three tandem C ₂H₂ fingers. Here, we review current information about the biochemical function and in vivo role for members of this subfamily. In general, NET family proteins are required during embryonic development. They appear to act by regulating transcription, most likely as repressors, although they are unlikely to bind DNA directly. In the future, it will be important to directly test if NET family proteins control transcription of specific target genes, perhaps via interactions with DNA-binding transcription factors, as well as to further explore their function in vivo.