Calcium Triggered Compound Fusion at Ribbon Synapses During Exocytosis

Background Exocytosis in photoreceptors involves fusion of vesicles with the plasma membrane at base a specialized proteinaceous electron-dense structure known as synaptic ribbon. The molecular mechanisms underlying exocytosis ribbon synapses are not well understood. Research suggests compound model where undergo homotypic forming larger prior to membrane. But how this process is mediated remains unclear. Ca2+ triggers several forms different types eukaryotic cells through activation SNARE complex. SNARE-mediated membranes triggered by calcium sensor Synaptotagmin, but much about whether applies fusion. Here, we report that, like typical exocytosis, influx. Method To examine role fusion, performed vesicle purification experiments from Mus musculus (C57BL/6 WT) retina. Brain tissue was also used control expected no Retina and brain were dissected, homogenized, ultracentrifuged. supernatant incubated 2mM for 5 minutes then Ca2+samples controls containing Ca2 isolated using magnetic beads coupled rho1D4 monoclonal antibody. Vesicles negatively stained viewed under TEM. Vesicle sizes samples determined via blind analysis ImageJ. Results In retina samples, exogenous caused significant increase size when diameter ranged 30nm 250nm. This effect seen 60nm. No large any samples. Conclusion Our research supports synapses. We suggest that retina, formed during result smaller fusing each other has process. Future studies investigating sensors such synaptotagmin will help further elucidate its therapeutic potential neurological disorders.