Fig 2: Comparison of SK2-LI obtained with antibodies directed against the C-terminal and the N-terminal region of the SK2 peptide. Adjacent sections of SK2-LI detected with ANTI-CSK2 (a, c, e, g and i) and Anti-NSK2 (b, d, f, h and j). In hippocampus, SK2-LI was detected in molecular layer and in strata oriens and radiatum of CA1 (a, b). In granule cell layer, SK2-LI could be detected mainly in the plasma membrane (c, d). In pyramidal layer, somata and apical dendrites showed expression of SK2 peptide (e, f). In the amygdala, SK2-LI in basolateral nuclei was detected in cell somas (g, h). In the neocortex, SK2-LI detected with the N-terminal antibody showed only moderate immunoreactivity in cells of layer V (j), while SK2-LI detected with Anti-CSK2 was found as well in layer IV and VI (i). sr stratum radiatum, sp stratum pyramidale, so stratum oriens, slm stratum lacunosum moleculare, ml molecular layer, gl granule cell layer, pl pleomorphic cell layer, BLA basolateral amygdala, IV, V, VI layers of the cortex, Scale bar 200 µm in a, b; 30 µm in c–f; 60 µm in g–j

Fig 3: Western blot of the C-terminal (Anti-CSK2) and the N-terminal (Anti-NSK2) antibody directed against the SK2 peptide (a). A band corresponding to the standard SK2 channel isoform was detected at ~52 kD with both antibodies in human and mouse brain tissue. Anti-CSK2 detected three another bands corresponding to two short isoforms and the long isoform of SK2 in human brain. Anti-NSK2 detected signals corresponding to the standard isoform and the long isoform, while the signals for short isoforms were missing. Schematic illustration of Anti-CSK2 and Anti-NSK2 recognition sites (b). hbr human brain, mbr mouse brain, Anti-CSK2 C-terminal SK2 antibody, Anti-NSK2 N-terminal SK2 antibody, Anti-NSK2PB peptide block of Anti-NSK2