Fig 1: Substitutions in the CaMK domain of CASK do not alter interactions with Mint1 and Neurexin, whereas binding to Veli is slightly increased for the E115K variant.(A) mRFP-tagged CASK-WT and mutants or mRFP alone were coexpressed with Mint1 in HEK293T cells. mRFP-tagged proteins were immunoprecipitated from cell lysates, and inputs (IN) and precipitates (IP) were analysed by Western blotting using antibodies against GFP- and mRFP-tags, and anti-Veli. (B, C) Quantitative analysis of results shown in (A). Coprecipitation efficiency was determined as the ratio of Mint1 (B) or Veli (C) IP signal, divided by the CASK IP signal. (D, E) mRFP-tagged CASK variants were coexpressed with HA-tagged Neurexin, and mRFP-tagged proteins were immunoprecipitated as in (A). Quantitation in (E), performed as in (B) and (C), shows that Neurexin-1ß binding was not affected by CASK variants. The mean ± SD is shown with each data point representing an independent transfection experiment. Significance was determined by one-way ANOVA with post hoc Dunnett’s multiple comparisons test or two-tailed t test; *P = 0.05; n = 3–4.