Metabolism of Triacylglycerol

METABOLISM OF TRIACYLGLYCEROL

• Triacylglycerol contains one molecule of glycerol and 3 molecules of fatty acid.
• Occurs in liver, adipose tissue, intestinal mucosal cells.
• Organelle- endoplasmic reticulum.
• 3 steps-

1. Fatty acid to acyl CoA by Acyl CoA synthase (thiokinase)
2. Glycerol to glycerol-3-phosphate (formed from glucose-3- phosphate dehydrogenase in adipose tissue) by glucose kinase.
3. Phosphatidate undergoes hydrolytic dephosphorylation which is esterified to form triacylglycerol.

• In adipose tissues- insulin enhances triacylglycerol synthesis.
• In Diabetes, glycerol-3-phosphate is hampered leading to decrease triglyceride synthesis.
• Triglyceride is the major lipid for adipose tissues.

Triacylglycerol hydrolysis (lipolysis)-

• Triacylglycerol (stored fat) is degraded.
• Enzyme- hormone sensitive lipase.
• Lipolysis refers to hydrolysis of triacylglycerol in adipose tissues. 

Regulation of lipolysis-

• Hormone sensitive lipase activated by-
• Epinephrine
• Catecholamines
• Thyroid hormones
• Growth hormone
• ACTH
• Glucocorticoids 

Hormone sensitive lipase inactivated by-

• Insulin
• Prostaglandin