Association of cytosolic lipids with fatty acid synthase from lactating mammary gland.
1. Membrane-free cytosol contained over 4% of both the total lipids and phospholipids present in homogenates of lactating rat mammary gland, and much of this lipid was associated with a high molecular weight complex isolated from cytosol by gel exclusion chromatography or by density gradient centrifugation. 2. This complex principally consisted of polypeptides with apparent molecular weights of 220 and 116 kDa. Lipids associated with this complex were transferred to endoplasmic reticulum and to intracellular lipid droplet precursors of milk lipid globules upon incubation in a cell-free system. 3. This lipoprotein complex was abundant in cytosol from lactating mammary gland, but was diminished in amount in cytosol from involuted mammary glands. The 220 kDa constituent of this complex was identified as the monomer of fatty acid synthase. 4. These results suggest that fatty acid synthase complex in lactating mammary gland may function in transfer of lipids necessary for formation or growth of lipid droplet precursors of milk lipid globules.
Keon
B H
BH
Department of Biochemistry and Nutrition, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Ghosal
D
D
Keenan
T W
TW
D000818:Animals; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000378:metabolism*; D005260:Female; D007774:Lactation / Q000502:physiology*; D050356:Lipid Metabolism; D008074:Lipoproteins / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000201:enzymology*; D008892:Milk / Q000378:metabolism; D008970:Molecular Weight; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D008074:Lipoproteins; D010743:Phospholipids; D064429:Fatty Acid Synthases