The classical cap structure is a 7-methylguanosine moiety connected to the mRNA via a triphosphate linkage at 5'-end (m7GpppG or m7G). It can be recognized by several specialized proteins involved in mRNA transport, translation, translational repression and degradation. 6-thioguanosine (s6G) is a photosensitive molecule that can photo-crosslink to both proteins and nucleic acids to study cap-protein and cap-nucleic acid interactions at the molecular level.https://mrna.creative-biolabs.com/6-thioguanosine-containing-cap.htm