The long term objective of this proposal is the elucidation of the function(s) of non-erythroid spectrin. There is increasing evidence that challenges the prevailing view that non-erythroid spectrin acts only as a major structural component in a submembranous network similar to that found in red blood cells. In several cell types, spectrin is distributed in a non-random manner, often at some distance from the plasma membrane. Moreover, its subcellular distribution can be modulated by certain stimuli. Based on the extensive literature on non- erythroid spectrin, basic concepts regarding its function are now beginning to emerge. Spectrin has been implicated in various membrane- related events including membrane trafficking membrane receptor/micro- filament interactions and establishment/maintenance of membrane domains. In this study, a combination of immunological, biochemical and morphological techniques will be used to examine the function of spectrin in three cell types, the lymphocyte, the neuron and the enterocyte. Spectrin organization and dynamics will be studied in relation to cell-specific functional and developmental processes (i.e. lymphocyte activation, axonal transport, synaptic transmission and enterocyte maturation/development). Ultrastructural immunolocalization procedures developed in this laboratory will be used for detailed analysis of the spectrin skeleton (spectrin and associated proteins) during particular cellular events. Observed localization patterns will be interpreted in relation to emerging concepts of spectrin function. Since the localization of a protein is intimately related to its function, this approach should provide valuable insight regarding the cellular role(s) of this protein. In future studies, putative functions of non-erythroid spectrin will be tested by introduction of anti-spectrin antibodies into living cells. It is anticipated that these studies will provide important and substantive information concerning the possible functions of spectrin.
