Differential expression of the presynaptic cytomatrix protein bassoon among ribbon synapses in the mammalian retina

Abstract

Bassoon is a 420-kDa presynaptic protein which is highly concentrated at the active zones of nerve terminals of conventional synapses, both excitatory glutamatergic and inhibitory GABAergic, in rat brain. It is thought to be involved in the organization of the cytomatrix at the site of neurotransmitter release. In the retina, there are two structurally and functionally distinct types of synapses: ribbon and conventional synapses. Antibodies against bassoon were applied to sections of rat and rabbit retina. Strong punctate immunofluorescence was found in the outer and inner plexiform layers. Using pre- and post-embedding immunostaining and electron microscopy, bassoon was localized in the out..