This book focuses on GPI-anchored molecules in biomembranes, their organization, biosynthesis, function as receptors and use as engineered molecules. An extensive chapter is also devoted to discussing the structures of microbial GPI-anchored molecules and bioactivities on mammalian host cell membranes. The reviews of this book are intended to convey the up-to-date view of how GPI-anchored biomolecules interact with and function in membranes.