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Acyltransferase activities in the yolk sac membrane of the chick embryo
Author(s) -
Murray Alison M. B.,
Denis Raphael,
Speake Brian K.
Publication year - 1999
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-999-0442-0
Subject(s) - monoacylglycerol lipase , acyltransferase , biochemistry , yolk , microsome , biology , embryo , carnitine , enzyme , chemistry , food science , microbiology and biotechnology , endocannabinoid system , receptor
The activities of some enzymes of glycerolipid synthesis and fatty acid oxidation were measured in subcellular fractions of the yolk sac membrane (YSM), an extra‐embryonic tissue that mediates the transfer of lipid from the yolk to the circulation of the chick embryo. The activities of monoacylglycerol acyltransferase and carnitine palmitoyl transferase‐1 in the YSM (respectively, 284.8±13.2 nmol/min/mg microsomal protein and 145.6±9.1 nmol/min/mg mitochondrial protein; mean ±SE; n =4) at day 12 of development appear to be the highest yet reported for any animal tissue. Also, the carnitine palmitoyl transferase‐1 of the YSM was very insensitive to inhibition by malonyl CoA. The maximal activities of glycerol‐3‐phosphate acyltransferase and diacylglycerol acyltransferase in the YSM (respectively, 26.7±2.2 and 36.1±2.1 nmol/min/mg microsomal protein) were also high compared with the reported values for various animal tissues. The very high enzymic capacity for glycerolipid synthesis supports the hypothesis that the yolk‐derived lipids are subjected to hydrolysis followed by reesterification during transit across the YSM. The monoacylglycerol pathway appears to be the main route for glycerolipid resynthesis in the YSM. The results also suggest that the YSM has the capacity to perform simultaneously β‐oxidation at a high rate in order to provide energy for the lipid transfer process.