The study of molecular mechanism of Snapin in neurotransmission

MasterSnapin was identified by Zu-Hang Sheng group in 1999 as not only SNAP25 binding protein, but also modulation factor between SNARE(Soluble N-ethyl maleimide sensitive factor Attachment protein REceptor) and Synaptotagmin. But, the definite function of Snapin in neuron still has been debated by many groups of scientists. So, we indirectly verified whether that Snapin can interact with SNARE by means of in vitro vesicle reconstitution methods. Interestingly, The effect of Snapin, which has many positive amino acid residues in their protein sequence, in vesicle Docking/fusion was significantly reduced by negative charged lipid like PS(Phosphatidyl Serine). S50D mutant, which shows mimic effect of S50 phosphorylation by PKA(cAMP-dependent Protein kinase A) showed relived inhibition of PS. On the basis of our results, we insist that Snapin closely interact with SNARE and S50 phosphorylation of Snapin by cAMP depedent PKA could act as docking signal, which may be link between secondary molecule like cAMP and SNARE-mediated membrane fusion