Lipid metabolism by The gall-bladder. II. The in vitro conversion of lysophosphatidylcholine to phosphatidylcholine.

Lysophosphatidylcholine acyltransferase, which catalyzes the acylation of lysophosphatidylcholine with fatty acid coenzyme A to form phosphatidylcholine, was assayed in gall-bladder mucosa. In guinea pig gall-bladder the activity parallels that of the microsomal enzyme, glucose-6-phosphatase with 3--4-fold enrichment of the activity in the microsomes. Studies with saturated and unsaturated substrates demonstrated highest activity when oleoyl coenzyme A and palmitoyl lysophosphatidylcholine were used and the lowest activity when palmitoyl coenzyme A and palmitoyl lysophosphatidylcholine were used. This activity was demonstrated in the dog, rabbit, cat, calf and human gall-bladder mucosa; however, a wide variation in the amount was observed. Lysophospholipase, which catalyzes the hydrolysis of lysophosphatidylcholine to glycerophosphorylcholine and fatty acid, was also demonstrated in gall-bladder mucosa.