My research interests are in the ultrastructure of synapses, in the correlation of this ultrastructure with neurotransmitter release and detection, and in the development of synapses from initially undifferentiated cell-cell contacts.
Current research is on the ACh receptor clusters formed by rat muscle cells in tissue culture, which are a model for the postsynaptic membrane and combine a high concentration of receptor molecules with strong attachments to the substrate. Receptor-rich regions contain a flexible membrane skeleton containing spectrin, dystrophin, utrophin, and other associated proteins. I use immunogold labeling combined with freeze fracture and freeze etching to determine the organization of these proteins as well as those anchoring the cytoskeleton to the substrate, in order to understand the architecture created by these proteins and how the complex mosaic pattern of AChR clusters is created, as a way of understanding the mechanism of differentiation of the postsynaptic membrane. Additionally, I am studying (1) the surface glycoproteins of receptor cells in taste buds of the rat tongue, to determine how taste reception and taste bud organization are maintained despite constant turnover of individual receptor cells, and (2) the involvement of G proteins of taste receptor cells in the signaling of taste sensations.
Pumplin, D.W., Yu, C., and D.V. Smith, 1997. Light and dark cells of rate vallate taste buds are morphologically distinct cell types. J. Comp. Neurol. 378:389-410.