In this volume of Reviews there are three outstanding articles, one on phspholipase D, an enzyme that is widely distributed in bacteria, protozoa, fungi, plants and animals. Phospholipase D carries out a transphosphatidylation reaction, which is unique to this enzyme. This review is focussed on mammalian PLDs. The second review deals with endotoxin tolerance, the term which describes the phenomenon that immune responses and metabolic changes are mitigated after repeated LPS administration. The third article summarizes the current knowledge relevant to understanding the molecular basis of GPCR function and focusses on the underlying mechanisms of GPCR malfunctions responsible for diferent human diseases.

Contributions by: J.H. Exton, M.D. Lehner, T. Hartung, T. Schoeneberg, A. Schulz, T. Gudermann