LC3, a mammalian homologue of yeast ATG8, is a soluble protein that is distributed ubiquitously in mammalian tissues and cultured cells. LC3 has been studied most extensively and is frequently used as an autophagy marker in mammals. Newly translated LC3 (proLC3) is immediately processed at the C-terminus in order to form LC3-I. During autophagy, autophagosomes engulf cytoplasmic components, including cytosolic proteins and organelles. Concomitantly, a cytosolic form of LC3 (LC3-I) is conjugated to phosphatidylethanolamine to form LC3-phosphatidylethanolamine conjugate (LC3-II), which is recruited to autophagosomal membranes.