Source: Human Cells. MW :11.4kD. Recombinant Human Motilin is produced by our Mammalian expression system and the target gene encoding Phe26-Lys115 is expressed with a 6His tag at the C-terminus. Promotilin is a 115 amino acids protein that belongs to the motilin family. It is a secreted protein that plays an important role in the regulation of interdigestive gastrointestinal motility and indirectly causes rhythmic contraction of duodenal and colonic smooth muscle.