Antibiotic; inhibits GlcNAc phosphotransferase (GPT). Blocks the formation of N-glycosidic linkages by inhibiting the first step in glycoprotein synthesis. Activity induces ER stress and causes G1 arrest. Tunicamycin contains four main components as follows: Homolog A, n=8, C37H60N4O16, molecular weight = 816.90 Homolog B, n=9, C38H62N4O16, molecular weight = 830.93 Homolog C, n=10, C39H64N4O16, molecular weight = 844.95 Homolog D, n=11, C40H66N4O16, molecular weight = 858.99 The composition of this product will vary from batch to batch and can be found on the relevant certificate of analysis.