Research Interests

Our long term goals have been the correlation of surface membrane macromolecular diffusional dynamics with cell (or membrane) function, and the development of new approaches for evaluating diffusional dynamics parameters for both lipids and proteins. Fluorescence redistribution after photobleaching (FRAP), total internal reflection FRAP (TIR-FRAP), fluorescence correlation spectroscopy (FCS), single particle tracking (SPT), and confocal microscopy methods have been used to establish macromolecular distribution and mobility characteristics. These approaches were utilized to examine the diffusional behavior of such seemingly diverse systems as membrane proteins on sperm cell surfaces, thy-1 antigen on the surface of 3T3 fibroblasts, the distribution and diffusional dynamics of EGF receptor and the ICAM-1 adhesion molecule on fibroblast and endothelial cell surfaces. Work has concentrated on two specific areas: the factors that restrict and control the rate of lateral diffusion of integral membrane proteins and lipids; and the mechanisms that produce and maintain specialized domains on the surfaces of differentiated cells. It is expected that such studies will continue to give new insight into the structural organization of the cell, and the dynamics of intracellular interactions.

Selected Publications

Cowan, A.E., E.M. Olivastro, D.E. Koppel, C.A. Loshon, B. Setlow, and P. Setlow. 2004. Lipids in the inner membrane of dormant spores of Bacillus species are largely immobile. Proc Natl Acad Sci U S A. 101:7733-8. Epub 2004 May 4.

Cowan A.E., Koppel DE, Setlow, B., and Setlow P. 2003. A soluble protein is immobile in dormant spores of Bacillus subtilis but is mobile in germinated spores: implications for spore dormancy. Proc Natl Acad Sci U S A. 2003 Apr 1;100(7):4209-14. Epub 2003 Mar 19.

Cowan, A.E., D.E. Koppel, L.A. Vargas, and G.R. Hunnicutt. 2001. Guinea pig fertilin exhibits restricted lateral mobility in epididymal sperm and becomes freely diffusing during capacitation. Dev Biol. 236:502-9.