A major project in our laboratory concerns spatiotemporal aspect of cell signaling in CD4+ helper T lymphocytes with the focus on cholesterol-rich membrane nanodomains, also known as lipid rafts. Lipid rafts show high representation of sphingolipids, glycosyl-phosphatidylinsitol (GPI)-anchored proteins (e.g., Ly-6 proteins) and a number of lipid modified signaling molecules. These membrane nanodomains are compositionally heterogeneous, dynamic and exist as 10-100 nanometer size structures in a variety of cell types. The nanodomains coalesce during cellular interactions to form larger raft platforms. A significant research interest in my laboratory is to examine their role in orchestrating signals on the plasma membrane of naive CD4+ T cells after it interacts with antigen-presenting cells (APC) (e.g., dendritic cell), presenting a foreign antigen. Second project in my laboratory focuses on the role of Ly-6 proteins in regulating cell signaling. Products of Ly-6 gene family are cysteine-rich, 12-14 Kda, three-fingered (similar to some venom toxins), GPI-anchored proteins, first identified on lymphocyte cell surface in mice. Ly-6 proteins possess cell signaling and cell adhesion properties. We are investigating the mechanism how Ly-6A, one member of Ly-6 family, signals and regulates signals through other receptors in spite of the absence of both the transmembrane and cytoplasmic domains. One idea we are exploring concerns lipid rafts where Ly-6A protein localizes. How does Ly-6A protein co-opts this membrane structure and its contents (receptors and other signaling molecules) to communicate to the cell interior? To understand the spatiotemporal regulation of cell signaling in CD4+ T cells and role of lipid rafts and Ly-6 proteins in it, we have developed novel methods and approaches to analyze lipid rafts either on the subpopulation basis (Raft ELISA) or single raft-basis (Raft EM and SEM). Understanding spatiotemporal signaling mechanism in CD4+ T cells is significant, as without CD4+ T cells and its functional responses, the entire immune system severely weakens and shows an inability to defend against opportunistic infections and eruption of tumors, as demonstrated in advanced stages of HIV infection.