Upon depolarization, neurotransmitters such as glutamate are relased from the presynaptic side and open ligand-gated ion channels such as glutamate receptors in the postsynaptic membrane. The strength of signal transmission can be modulated by earlier activities of a synapse, and this effect can be long-lasting. A change in synaptic strength is thought to be the physiological basis of learning and memory. Electrical high-frequency stimulation of certain neuronal pathways eleveates synatic signal transmission for several hours. We are characterizing the regualtion of these postsynaptic channels by those kinases and proteases.
NMDA receptors interact with postsynaptic proteins known as SAPs and with alpha-actinin.
These cytoskeletal proteins may regulate the postsyaptic localization and function of NMDA receptors. Cyclins promote the progression of proliferating cells throught he cell cycle by regulating the activity of cyclin dependent kinases. Recently, we have cloned and characterized homologous members of a novel family of cyclins which are expressed in neuronal tissue. At least one member has specifically been localized to differentiated neurons. Since neurons are post-mitotic and do not proliferate, neuronal cyclins are likely to be involved in functions distinct from those promoting cell division.