In the late 1970s, PEMT activitywas identified in various tissues (e.g.,
bovine adrenal medulla and mammary gland). However, because the
activity was very low compared to that in liver, it was surprising that
a number of physiological changes (e.g. histamine release from mast
cells and leukocyte chemotaxis) were attributed to phospholipidmethylation
[53–55]. The activity of PEMT in these non-hepatic cellswas 0.1%
or lower than that in rat liver microsomes [56].