Distinct functional domains in emerin bind lamin A and DNA-bridging protein BAF.
Loss of emerin, a lamin-binding nuclear membrane protein, causes Emery-Dreifuss muscular dystrophy. We analyzed 13 site-directed mutations, and four disease-causing mutations that do not disrupt emerin stability or localization. We show that emerin binds directly to barrier-to-autointegration factor (BAF), a DNA-bridging protein, and that this binding to BAF requires conserved residues in the LEM-motif of emerin. Emerin has two distinct functional domains: the LEM-domain at the N-terminus, which mediates binding to BAF, and a second functional domain in the central region, which mediates binding to lamin A. Disease mutation Delta95-99 mapped to the lamin-binding domain and disrupted lamin A binding in vitro. Two other disease-linked residues, Ser54 and Pro183, mapped outside the BAF and lamin-binding domains, suggesting that emerin may have additional functional domains relevant to disease. The disease-linked emerin proteins all remained active for binding to BAF, both in vitro and in vivo, suggesting that disease can result from the loss of specific molecular interactions between emerin and either lamin A or putative novel partner(s). The demonstration that emerin binds directly to BAF, coupled to similar results for LAP2, provides proof in principle that all LEM-domain nuclear proteins can interact with BAF, with interesting implications for chromatin attachment to the nuclear envelope.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.