Fig. 4

PS1 interacts with Syt1 on endogenous level. a Syt1 co-immunoprecipitates with PS1 from mouse hippocampi. The co-IP assay was conducted using anti-PS1 CT and anti-PS1 NT antibodies for pull-down; the detection antibodies are indicated to the left of each blot, n = 3. b PS1 co-immunoprecipitates with Syt1 from mouse cortical primary neurons. The co-IP assay was conducted using anti-Syt1 antibody for pull-down; the detection antibodies are indicated to the left of the blot. Other γ-secretase components pulled-down with Syt1 in the 1 % CHAPSO buffer are shown, n = 4. c Syt1 co-immunoprecipitates with PS1 from synaptoneurosome (SNS) fractions in a Ca²⁺-dependent manner. SNS were solubilized in 1 % CHAPSO buffer in the presence or absence of 2 mM CaCl₂. N-terminal PS1 antibody (or IgG control) were used for pull-co-immunoprecipitated with PS1 NTF (normalized to the respective PS1 NTF band intensities). All the data are presented as mean ± SEM, n = 4. Statistical significance was determined using the unpaired student t-test, * p < 0.05. d Syt1 co-immunoprecipitates with PS1 from mouse SNSs solubilized in 1 % TritonX-100 buffer in the presence of 2 mM CaCl₂ when anti-PS1 NT, but not anti-PS1 loop or anti-PS1 CT antibody, is used for pull-down. The detection antibodies are indicated on the left side of the blot. Schematic representation of the PS1 molecule; the presumed Syt1 interaction sites are shown. PS1 presenilin 1, Syt1 synaptotagmin 1, IP immunoprecipitation, CT C-terminus, NT N-terminus, NTF N-terminal fragment