SAM-IV riboswitches are a kind of
riboswitch that specifically binds
S-adenosylmethionine (SAM),[1] a cofactor used in many methylation reactions. Originally identified by
bioinformatics,[2] SAM-IV riboswitches are largely confined to the
Actinomycetales, an order of
Bacteria. Conserved features of SAM-IV riboswitch and experiments imply that they probably share a similar SAM-binding site to another class of SAM-binding riboswitches called
SAM-I riboswitches. However, the scaffolds of these two types of riboswitch appear to be quite distinct. The structural relationship between these riboswitch types has been studied.[3][4]