The tunicamycins are a family of lipophilic nucleosides with fatty acids conjugated to an aminoglycoside group. The complex comprises the analogues, tunicamycins I to X. This composition is typical of other products less precisely described as tunicamycins A to D. The tunicamycins act by blocking the formation of N-glycoside linkages to proteins via inhibition of formation of dolichol monophosphate from N-acetylglucosamine-1-phosphate. Tunicamycin blocks the synthesis of all N-linked glycoproteins (N-glycans) and causes cell cycle arrest in G1 phase. Tunicamycins are broadly active against prokaryotes, eukaryotes and viruses.