PT  - JOURNAL ARTICLE
AU  - David Zenisek
AU  - Nicole K. Horst
AU  - Christien Merrifield
AU  - Peter Sterling
AU  - Gary Matthews
TI  - Visualizing Synaptic Ribbons in the Living Cell
AID  - 10.1523/JNEUROSCI.2886-04.2004
DP  - 2004 Nov 03
TA  - The Journal of Neuroscience
PG  - 9752--9759
VI  - 24
IP  - 44
4099  - http://www.jneurosci.org/content/24/44/9752.short
4100  - http://www.jneurosci.org/content/24/44/9752.full
SO  - J. Neurosci.2004 Nov 03; 24
AB  - Visual and auditory information is encoded by sensory neurons that tonically release neurotransmitter at high rates. The synaptic ribbon is an essential organelle in nerve terminals of these neurons. Its precise function is unknown, but if the ribbon could be visualized in a living terminal, both its own dynamics and its relation to calcium and vesicle dynamics could be studied. We designed a short fluorescent peptide with affinity for a known binding domain of RIBEYE, a protein unique to the ribbon. When introduced via a whole-cell patch pipette, the peptide labeled structures at the presynaptic plasma membrane of ribbon-type terminals. The fluorescent spots match in size, location, number, and distribution the known features of synaptic ribbons. Furthermore, fluorescent spots mapped by confocal microscopy directly match the ribbons identified by electron microscopy in the same cell. Clearly the peptide binds to the synaptic ribbon, but even at saturating concentrations it affects neither the morphology of the ribbon nor its tethering of synaptic vesicles. It also does not inhibit exocytosis. Using the peptide label, we observed that the ribbon is immobile over minutes and that calcium influx is concentrated at the ribbon. Finally, we find that each ribbon in a retinal bipolar cell contains ∼4000 molecules of RIBEYE, indicating that it is the major component of the synaptic ribbon.