alpha-Endorphin is the 1-16 fragment of beta-Endorphin. alpha-Endorphin is a substrate for transglutaminase and both alpha-Endorphin and alpha-Endorphin's acetylated form are found in intermediate and anterior lobes of the pituitary. alpha-Endorphin appears to bind to neuronal opiate receptors, but does not bind to beta-Endorphin receptors in lymphocytes, vasculature, or vas deferens. Stimulatory effects on immune system function have been reported.