Interaction of hCLIM1, an Enigma family protein, with alpha-actinin 2

Enigma proteins are proteins that possess a PDZ domain at the amino termina l and one to three LIM domains at the carboxyl terminal. They are cytoplasm ic proteins that are involved with the cytoskeleton and signal transduction pathway. By virtue of the two protein interacting domains, they are capabl e of protein-protein interactions. Here we report a study on a human Enigma protein hCLIM1, in particular. Our study describes the interaction of the human 36kDa carboxyl terminal LIM domain protein (hCLIM1), the human homolo gue of CLP36 in rat, with alpha-actinin 2, the skeletal muscle isoform of a lpha-actinin. hCLIM1 protein was shown to interact with alpha-actinin 2 by yeast two-hybrid screening and immunochemical analyses. Yeast two-hybrid an alyses also demonstrated that the FIM domain of hCLIM1 binds to the EF-hand region of alpha-actinin 2, defining a new mode of LIM domain interactions. Immunofluorescent study demonstrates that hCLIM1 colocalizes with alpha-ac tinin at the Z-disks in human myocardium. Taken together, our experimental results suggest that hCLIM1 is a novel cytoskeletal protein and may act as an adapter that brings other proteins to the cytoskeleton. J. Cell. Biochem . 78:558-565, 2000. (C) 2000 Wiley-Liss, Inc.