THE SECRETION OF INTESTINAL ALKALINE-PHOSPHATASE (IAP) FROM THE ENTEROCYTE

Rat intestinal alkaline phosphatase exists in two separate forms, diff ering markedly in the carboxyterminal coding region, as well as in the 3' untranslated regions. It is secreted bound to a phospholipid-rich particle (surfactant-like particle) which appears to have unique prope rties, but whose role is still uncertain. Evidence is presented to sug gest that intestinal alkaline phosphatase secretion is mediated by thi s particle. The challenge for the future is to study the biology of th e surfactant-like particle, to ascertain its role in gut physiology, a nd to determine how the dual alkaline phosphatases are involved in thi s specialized secretory apparatus.