A NATO Advanced Study Institute on "New Developments in Lipid-Protein Interactions and Receptor Function" was held on the Island of Spetsai, Greece, from August 16-27, 1992. This Institute was organized to bring together researchers in the field of membrane organization and dynamics with those actively involved in studies on receptor function, signal transduction mechanisms and gene regulation. 2 Presentations and discussions focussed on the regulation of intracellular Ca +-levels, on the second messengers derived from inositol lipids and on the specific phospholipase C isozymes involved in these processes. A major focus was on G-proteins and the effect of lipid anchors on their function. These principles of regulation were further discussed in the context of receptors for acetylcholine, lysophosphatidic acid and low-density lipoproteins. In addition, various aspects of the genomic regulation of cell growth and differentiation by transcription factors were presented. These topics were put into perspective by discussing the most recent developments in lipid-protein interactions, protein insertion into membranes, membrane lipid organization and lipid dynamics as mediated by phospholipid transfer proteins. This book presents the content of the major lectures and a selection of the most relevant of the most important topics posters. These proceedings offer a comprehensive account presented during the course of the Institute. The book is intended to make these proceedings accessible to a large audience.

1.1 Mechanism of Action of Glucocorticoid Hormones The current model of glucocorticoid hormone action is summarized in Fig. 1. After synthesis, glucocorticoids are secreted into the blood stream and trans- ported to target cells where they bind with high affinity (K-1O-9M) and d specificity to the intracellular glucocorticoid receptor (GR) protein. The sub- cellular localization of hormone-free GR is still a controversial issue. However, most data support the idea that unliganded GR is in the cytoplasmic compartment or loosely associated with the nucleus (Picard and Yamamoto 1987; Gustafsson et al. 1987 and references therein; LaFond et al. 1988; Gasc et al. 1989). Upon ligand binding, GR is activated into a form capable of interacting with DNA. The mechanism of GR activation probably involves a conformational change and dis- sociation from nonreceptor components, e.g., the 90-kDA heat shock protein (hsp90: Pratt et al. 1988; Bresnick et al. 1989; Denis and Gustafsson 1989). The subcellular location of activated GR has been firmly established to be inside the nucleus. In vivo, the hormone-receptor complex interacts with specific DNA Activation r:::.. ~ qc [!3-GC ...&.GC~ j ~ ? , BIOLOGICAL EFFECTS " t , Active Protein , , ~Vl\lent.