Serotonylation occurs in multiple tissues, smooth muscular and non-smooth muscular.

<p>Serotonylation of proteins from homogenates of rat thoracic aorta, rat stomach fundus, rat small intestine and rat cerebral cortex. The right half of the blot shows inhibition of serotonylation by the TG inhibitor cystamine. Representative of three separate experiments, each using 2 samples from different animals.