Vollum Institute 1 article published in JoVE Biochemistry Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy Emery Haley*1, Wooyoung Choi*1, Chen Fan1, Weinan Sun2,3, Juan Du1, Wei Lü1 1Van Andel Institute, 2Vollum Institute, 3Janelia Research Campus This protocol describes techniques used to determine ion channel structures by cryo-electron microscopy, including a baculovirus system used to efficiently express genes in mammalian cells with minimum effort and toxicity, protein extraction, purification, and quality checking, sample grid preparation and screening, as well as data collection and processing.