Sticky fingers: zinc-fingers as protein-recognition motifs

Zinc-fingers (ZnFs) are extremely abundant in higher eukaryotes. Once considered to function exclusively as sequence-specific DNA-binding motifs, ZnFs are now known to have additional activities such as the recognition of RNA and other proteins. Here we discuss recent advances in our understanding of ZnFs as specific modules for protein recognition. Structural studies of ZnF complexes reveal considerable diversity in terms of protein partners, binding modes and affinities, and highlight the often underestimated versatility of ZnF structure and function. An appreciation of the structural features of ZnF–protein interactions will contribute to our ability to engineer and to use ZnFs with tailored protein-binding properties.