Emerin

Emerin is a small integral membrane protein of the inner nuclear membrane encoded by the EMD gene on the X chromosome. In humans it consists of about 254 amino acids (approximately 25 kDa) and features a nucleoplasmic N-terminal region that includes a LEM domain, plus a C-terminal transmembrane segment that anchors it to the inner nuclear membrane. The LEM domain enables interactions with barrier-to-autointegration factor (BAF) and chromatin, helping to organize the nuclear envelope.

Emerin interacts with lamins A and C (LMNA) and a network of nuclear envelope and chromatin-associated proteins, including LAP2, MAN1, and nesprins, forming multiprotein assemblies at the inner nuclear membrane. Through these interactions, Emerin participates in chromatin organization, regulation of gene expression, and mechanotransduction, transmitting cytoskeletal forces to the nucleus and influencing nuclear shape and genome function.

Expression of Emerin is widespread but highest in skeletal muscle and heart, consistent with the muscle-related phenotypes observed when EMD is mutated. Emerin is important for maintaining nuclear envelope integrity in muscle cells; loss or dysfunction of Emerin can disrupt nuclear morphology and alter transcriptional programs.

Clinical significance: Mutations in EMD cause X-linked Emery-Dreyfus muscular dystrophy (EDMD). Clinical features include early-onset muscle weakness, contractures, and cardiomyopathy. Mutations may disrupt Emerin localization, stability, or interactions, leading to defective nuclear architecture and altered gene regulation.

Discovery: Emerin was identified in 1995 as the disease-causing protein in X-linked Emery-Dreyfus muscular dystrophy.