DETECTION OF CELLULAR PROTEINS THAT INTERACT WITH THE NF2 TUMOR-SUPPRESSOR GENE-PRODUCT

The neurofibromatosis type 2 (Nn) gene was recently cloned, and the pr otein it encodes (merlin) was revealed to belong to a family of protei ns that link cytoskeletal components with proteins in the cell membran e. To elucidate the biological function of merlin, we produced a bacte rial fusion protein consisting of glutathione S-transferase and merlin and used it to detect five merlin-binding cellular proteins, designat ed p165, p145, p125, p85 and p70, by a protein-binding assay. p165 and merlin were phosphorylated on serine/threonine residues, and immunopr ecipitation showed that p85 bound the native form of merlin. Although the entire merlin-ezrin-radixin-moesin (MERM) homology domain of merli n was found to be essential for binding to all five proteins, the MERM homology domains of ezrin and moesin did not bind to any of the five proteins. Since most reported NF2 mutations are in the region we deter mined was necessary for binding, the mutations probably impair binding . Therefore, the formation of the protein complex is probably crucial for tumor suppression.