Protein Translocation Across the Endoplasmic Reticulum Membrane -- Preprotein Translocation through the Sec Translocon in Bacteria -- Protein Translocation in Archaea -- Structure of the SecYEG Protein Translocation Complex -- Membrane Protein Insertion in Bacteria from a Structural Perspective -- The Twin-Arginine Transport System -- Retro-Translocation of Proteins Across the Endoplasmic Reticulum Membrane -- Chloroplast Protein Targeting -- The Mitochondrial Protein Import Machinery -- Import of Proteins into Peroxisomes. This book addresses the most recent advances in the transport of proteins across a variety of biological membranes. In addressing this topic, this volume includes several new twists not previously addressed in the literature. In the last few years, the study of protein translocation has been revolutionized by the availability of structural information on many of the components and complexes involved in the process. Unlike earlier books written on protein translocation, this volume considers these advances. In addition, several chapters discuss facets of protein translocation from a systems biology perspective, considered by many to be the next paradigm for biological study. Readers of this book will come away with a deeper understanding of the problems facing researchers of protein translocation and see how the most modern biological techniques and approaches are being recruited to answer those questions. The chapters are also written such that problems awaiting future investigation are clearly presented.