Journal of Lipid Research, Vol 20, 246-253, Copyright © 1979 by Lipid Research, Inc.
Ontogeny of glycerolipid biosynthetic enzymes in swine liver and adipose tissue
DG Steffen, G Phinney, LJ Brown and HJ Mersmann
Enzymes associated with glycerolipid biosynthesis were examined in
microsomal fractions of liver and adipose tissue obtained from swine of
various ages. Generally, liver glycerophosphate acyltransferase,
phosphatidate phosphohydrolase, diglyceride acyltransferase, and choline
phosphotransferase activities were substantial at birth but increased 2- to
3-fold by day 14 postpartum, decreased at day 25, then increased at the
oldest ages studied (up to 155 days postpartum). In adipose tissue, enzyme
activities were low at birth and developed through day 25 in a pattern
generally similar to that observed in liver. In contrast to liver, the
adipose enzymes were depressed immediately postweaning (day 32) with
subsequent recovery. The observed decline in adipose tissue enzyme
activities expressed on a tissue basis at older ages was primarily the
result of increased adipocyte size, since the activities expressed on a
cell basis did not decline as rapidly. In both liver and adipose tissue,
phosphatidate was the major glycerolipid synthesized by the microsomal
glycerophosphate acyltransferase enzymes at all ages (generally greater
than 75%). The ratio of neutral lipids to phospholipids produced by
acylation of glycerophosphate was increased when a microsomal--cytosolic
preparation was used as a source of enzyme in contrast to a microsomal
preparation.