phosphatidylinositol

noun

phos·​phat·​i·​dyl·​ino·​si·​tol ˈfäs-fə-ˌtī-dᵊl-i-ˈnō-sə-ˌtȯl, fäs-ˌfa-tə-dᵊl-, -ī-ˈnō-, -ˌtōl 

: an acidic phospholipid that contains an inositol attached to the phosphate group of phosphatidic acid and is found especially in cell membranes where it is precursor to several substances that mediate cellular activity as second messengers

The parent phospholipid, phosphatidylinositol, can modulate the activity of several membrane-bound enzymes, including sodium-potassium adenosine triphosphatase, and mediate transmembrane signaling processes.

—Bruce J. Holub, The New England Journal of Medicine