Coimmunoprecipitation analysis for binding between Munc18-2 and syntaxin 11 proteins. All immunoprecipitation reactions were performed with exogenous constructs with the use of either an Ab specific for Flag (syntaxin 11) or for enhanced green fluorescent protein (EGFP; Munc18-2). No endogenous proteins were analyzed. Exposition time of the x-ray film was 15 seconds. Lanes 1 through 3 show control samples, lane 4 shows the Munc18-2 construct as identified as the main RNA product detected in 2 of our patient samples with a homozygous exon 15 splice-site mutation. Lane 5 shows an artificial construct that contains an in-frame deleted exon 15. Lanes 6 and 7 are constructs representing missense mutations with nearly absent syntaxin binding. All Munc18-2 constructs, representing the different kind of mutations, show comparable loss of binding for syntaxin.