Identification of mucus glycoprotein fatty acyltransferase activity in human gastric mucosa.

The enzymatic activity which catalyzes the transfer of palmitic acid from palmitoyl coenzyme A to gastric mucus glycoprotein was demonstrated in antral and fundic mucosa of normal human stomach. Subcellular fractionation studies revealed that with both types of mucosa the enzyme activity was present in the microsomal fraction. The antral and fundic mucosa also exhibited similar enzyme activities, showed identical pH optimum, and required detergent, NaF and dithiothreitol. Optimum enzymatic activity for fatty acylation of mucus glycoprotein was obtained with 0.5% Triton X-100, 25 mM NaF, and 2 mM dithiothreitol at a pH of 7.4. The 14C-labeled product of the reaction comigrated on CsCl density gradient centrifugation with gastric mucus glycoprotein and contained the ester-bound palmitic acid.