Symmetrical arrangement of proteins under release-ready vesicles in presynaptic terminals
Abhijith Radhakrishnan, Xia Li, Kirill Grushin, Shyam S. Krishnakumar, Jun Liu, James E. Rothman
Abstract
Significance Neuronal cells maintain a small number of synaptic vesicles (SVs) that are “primed,” i.e., ready to release upon receiving the triggering signal to allow for tightly regulated and rapid release of neurotransmitters. The proteins involved in this process are known, but how they assemble and operate together is poorly understood. Here we report the visualization of protein organization under primed SVs in cultured neurons under native conditions. Using cryoelectron tomography analysis, we find that there is a symmetric arrangement of exactly six protein densities at the docking interface, suggesting the fusion machinery is well ordered and prearranged for fast and precise release of neurotransmitters.