Sterol O-acyltransferase that catalyzes the formation of stery esters. Inhibited by the protoberberine derivative HWY-289 in a non-competitive manner. Inhibited by miconazole. Not inhibited by CI-976, polyoxin D, amphotericin B or nikkomycin Z. Transcription is induced by HWY-289, but not by CI-976. HWY-289 may deplete protein levels causing an increase in transcription. Belongs to the membrane-bound acyltransferase family. Sterol o-acyltransferase subfamily.