Linear B-cell epitopes in Lambert-Eaton myasthenic syndrome defined by cell-free synthetic peptide binding.

Lambert-Eaton Myasthenic Syndrome (LEMS) is a rare autoimmune disorder characterized by autoantibodies that bind to P/Q voltage-gated calcium channels at the neuromuscular junction. Using cell-free direct peptide binding in 12 LEMS patients, we find linear B-cell epitopes that reside on the extracellular peptide linkers between the S5-S6 transmembrane peptides of Domains II and IV. A major epitope is located within the S5-S6 linker peptide of Domain IV defined by the acidic amino acid sequence EDEDSDEDE.