Membrane transporters are an important group of proteins in physiology and disease. Their functions make them common drug targets, but their location in the lipid bilayers poses a tremendous challenge to researchers. The current stage of development of structural biology, in addition to new research tools, has largely facilitated the acquisition of knowledge about transporters and mechanisms. This Collection presents recent studies, covering bioenergetics, structure and functional characterization of various transporters, lipids-protein interactions, and novel research tool development.