Serotonin creatinine sulfate complex is a neurotransmitter.

Potent and selective corticotropin releasing factor receptor-1 (CRF1) agonist (Ki values are 1.5 and 224 nM for CRF1 and CRF2 receptors respectively). Increases ACTH levels and increases faecal pellet output in vivo following i.p. administration.

Human proinsulin, the single-chain peptide precursor of insulin, consists of the insulin A and B chains connected by the 31 amino acid C-peptide. Cleavage of proinsulin by proteolytic enzymes produces insulin and free C-peptide.