Bassoon is a ~420 kDa protein that is a localized at the presynaptic nerve terminals and is believed to play a role in the structural and functional organization of the synaptic vesicle cycle. Bassoon does not belong to any known protein families. It has been found in rat and mouse with sequence identity of the two proteins at 96%. The human BASSOON gene has recently been cloned and localized. Bassoon is predicted to contain two double-zinc fingers, three coiled-coil regions, and two polyglutamine domains. The polyglutamine domains in the C-terminus are of interest, since it is known that for some human proteins, such as Huntingtin, abnormal amplification of this region can cause late-onset neurodegeneration. Bassoon is concentrated at sites opposite to postsynaptic densities in synaptic terminals and in cultured neurons, it is found to colocalize with GABA (A) and glutamate (GluR1) receptors. Another presynaptic protein, Piccolo was found to colocalize with Bassoon in cultured hippocampal neurons. These observations suggested that they serve specific functions at synaptic junctions and may be involved in organization of the cytoskeleton at the site of neurotransmitter release.
neuronal double zinc finger protein; presynaptic cytomatrix protein; Protein bassoon; zinc finger protein 231