THE LIM DOMAIN IS A MODULAR PROTEIN-BINDING INTERFACE

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.