LIM domains are zinc-binding protein sequences that are found in a gro
wing number of proteins, including certain transcriptional regulators,
proto-oncogene products, and adhesion plaque constituents. Here we de
fine the biological activity of the LIM domain through studies of an a
dhesion plaque protein called zyxin that displays three C-terminal LIM
domains. We have used our ability to reconstitute complexes between z
yxin and its two known binding partners, alpha-actinin and the cystein
e-rich protein (CRP), to examine the involvement of LIM domains in pro
tein-protein interactions. We have determined that one of the three LI
M domains of zyxin is necessary and sufficient to support the associat
ion of zyxin with CRP. Our findings demonstrate that the LIM domain fu
nctions as a specific protein-binding interface.