The Protein Reviews series serves as a publication vehicle for reviews that focus on crucial contemporary and vital aspects of protein structure, function, evolution and genetics. Volume 20, Purinergic Receptors, has ten chapters. The first five chapters deal with various aspects of membrane binding. The first chapter focuses on the phox-homology (PX) domain, which is a phosphoinositide-binding domain conserved in all eukaryotes and present in forty-nine human proteins. The next chapter deals with the modeling of PH domains/phosphoinositides interactions. This is followed by a chapter on BAR domain proteins regulate Rho GTPase signaling. The BAR (BinAmphiphysinRvs) domain is a membrane lipid binding domain present in a wide variety of proteins, often proteins with a role in Rho-regulated signaling pathways. The fourth article presents AP180 N-terminal homology (ANTH) and Epsin N-terminal homology (ENTH) domains and discusses their physiological functions and involvement in disease. The fifth article reviews the polyphosphoinositide-binding domains and presents insights from peripheral membrane and lipid-transfer proteins. This is followed by a chapter on the physiological functions of phosphoinositide-modifying enzymes and their interacting proteins in Arabidopsis, then by a chapter on the molecular mechanisms of Vaspin action in various tissues such as adipose tissue, skin, bone, blood vessels, and the brain. The eighth chapter deals with exceptionally selective substrate targeting by the metalloprotease anthrax lethal factor followed by an article on Salmonella, E. coli, and Citrobacter type III secretion system effector proteins that alter host innate immunity. The last chapter presents New techniques to study intracellular receptors in living cells, with insights into RIG-I-like receptor signaling. Volume 20 is intended for research scientists, clinicians, physicians and graduate students in the fields of biochemistry, cell biology, molecular biology, immunology and genetics.