Mass spectrometric studies on mouse hippocampal synapsins Ia, IIa, and IIb and identification of a novel phosphorylation site at serine-546.

Synapsins are key phosphoproteins in the mammalian brain, and structural research on synapsins is still holding center stage. Proteins were extracted from hippocampal tissue and separated on two-dimensional gel electrophoresis (2-DE), and the spots were analyzed by MALDI-TOF-TOF and nano-LC-ESI-MS/MS. Synapsins Ia, IIa, and IIb were unambiguously identified and represented by 15 individual spots on 2-DE. Several serine phosphorylation sites were confirmed, and a novel phosphorylation site was observed at Ser-546 in synapsin IIa in all gels analyzed.