Loss of functional emerin, a nuclear membrane protein, causes X-linked recessive Emery–Dreifuss muscular dystro-phy. In a yeast two-hybrid screen, we found that emerin interacts with Btf, a death-promoting transcriptional repressor, which is expressedat high levels in skeletalmuscle. Biochemical analysis showed that emerin binds Btf with an equilibriumaffinity (KD)of100 nM. Using a collection of 21 clustered alanine-substitution mutations in emerin, the resi-dues required for binding to Btf mapped to two regions of emerin that flank its lamin-binding domain. .
