Zinc finger (Znf) domains are relatively small protein motifs which contain multiple finger-like protrusions that make tandem contacts with their target molecule. Some of these domains bind zinc, but many do not; instead they can bind other metals, or no metal at all. They were first identified as a DNA-binding motif in transcription factor TFIIIA from Xenopus laevis (African clawed frog), but now they are recognised to bind DNA, RNA, protein and/or lipid substrates PMID:10529348,PMID:15963892,PMID:15718139,PMID:17210253,PMID:12665246.

The ClpX heat shock protein of Escherichia coli is a member of the universally conserved Hsp100 family of proteins. ClpX is an ATPase which functions both as a substrate specificity component of the ClpXP protease and as a molecular chaperone. Structural domains comprising this superfamily share the structure of the N-terminal zinc finger domain. This domain is of the C4 type PMID:11278349 and is a member of the treble clef zinc finger family, a motif known to facilitate protein-ligand, protein-DNA, and protein-protein interactions and forms a constitutive dimer that is essential for the degradation of some, but not all, ClpX substrates PMID:14525985.