In this book, the authors present current research in the study of the molecular structure, physiochemical properties and interactions with the environment of cell membranes. Topics discussed in this compilation include the generation and characterisation of recombinant HM-1 single-chain anti-idiotypic antibodies and their applications; large conductance of calcium activated potassium channels from protein complexes to function in mitochondrial associated ER membranes; unexpected plasma membrane location for a disulphide isomerase protein; and the effects of surface charge and particle size of cell-penetrating peptide/nanoparticle complexes on cellular internalisation.