Neurons communicate primarily through chemical synapses that transmit signals by releasing transmitters that cause electrical changes in target neurons. Many of these same transmitters also initiate biochemical changes in the signalling machinery of the synapse itself. For example, it is now thought that memories are encoded when the signalling strength of appropriate synapses is permanently increased through biochemical mechanisms triggered by the repeated use of the synapse.
Neurotransmitters can trigger the activation of several signal transduction pathways.
We are studying the molecular organization of signal transduction systems in central nervous system synapses. We have found that the postsynaptic density, a specialization of the submembranous cytoskeleton seen at postsynaptic sites in the central nervous system, contains signal transduction molecules that may control the sensitivity of transmitter receptors, the size of receptor clusters, or perhaps the integrity of the adhesion junction that holds presynaptic terminals in place. Employing a combination of microchemical and recombinant DNA techniques, we have determined the structure of several proteins associated with postsynaptic densities. We are presently studying the associations of these proteins with each other and their specific roles in control of synaptic transmission with the ultimate goal of illuminating the function and the biochemical diversity of this specialized organelle. This enzyme is activated by autophosphorylation of a threonine located near the calmodulin-binding site.