Biochemical Characterization of Native Schwannomin/Merlin
Annual summary rept. 11 Aug 2004-10 Aug 2005
ILLINOIS UNIV AT CHICAGO
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Neurofibromatosis type 2 is an autosomal dominant disorder, characterized by the development of bilateral vestibular and spinal schwannomas, meningiomas, and ependymomas. The NF2 gene encodes a 595 amino acid polypeptide known as NF2 protein or Merlin or Schwanomin. During the purification of NF2 protein from human erythrocytes, we noticed striking biochemical similarities between NF2 protein and p55. We have previously established that p55, a palmitoylated membrane phosphoprotein, forms a ternary complex with protein 4.1 and glycophorin C. Notably, the Drosophila homologue of p55 functions as a tumor suppressor in epithelial and neuronal tissues. To test the hypothesis that p55 is a major binding partner for NF2 protein in the RBC membrane, we generated maltose binding protein fusions of recombinant NF2 protein and tested their binding to p55. Both amino and carboxyl halves of NF2 protein were tested in the binding assay. Our results indicate a direct interaction between the FERM domain of NF2 protein and p55. The binding between p55 and NF2 protein was quantified, and existence of this complex was demonstrated in human erythrocyte plasma membrane. This unexpected finding reveals a new paradigm integrating the known functions of p55 family of proteins with the pathophysiology of NF2 protein.
- Medicine and Medical Research