From Streptomyces lysosuperificus. Provided as a mixture of tunicamycin A (C14), B (C15), C (C16) and D (C17) homologs in the fatty acid chain. Potent inhibitor of GlcNAc phosphotransferase which thereby inhibits glycoprotein biosynthesis. Causes endoplasmic reticulum stress-induced autophagy and unfolded protein response. Arrests cell cycle in late G1.