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.