Very low density lipoprotein. Dissociation of apolipoprotein C during lipoprotein lipase induced lipolysis.
The fate of apo C in rat plasma very low density lipoprotein (VLDL) during lipolysis was studied using VLDL labeled specifically with 125I-labeled apo C and purified bovine milk lipoprotein lipase. Incubations were carried out in vitro and included serum-containing systems and albumin containing systems. Free fatty acids generation proceeded with time of incubation in the two systems. It, however, was enhanced 1.5--2 fold by the presence of serum. 125I-labeled apo C equilibrated between very low and high density lipoprotein (HDL) in both systems even when enzyme was not present in the incubation medium, or when the incubation was carried out at 0 degrees C. Upon initiation of lipolysis, more 125I-labeled apo C was transferred to HDL and the transfer was proportional to the magnitude of free fatty acids release. 125I-labeled apo C was also progressively removed from VLDL in the albumin-containing system, although no known lipoprotein acceptor to apo C was present in the medium. The 125I-labeled apo C was recovered predominantly with the medium fraction of d greater than 1.21 g/ml (60--70%), and to a lesser degree with that of d= 1.019--1.21 g/ml. However, the relationship between lipolysis (measured as free fatty acids release) and removal of 125I-labeled apo C from VLDL were indistinguinshable in the albumin containing system and the serum containing system. On the basis of these observations, it is postulated that the removal of apo C during lipolysis of VLDL reflects the nature of the partially degraded VLDL particles, and is independent of the presence of a lipoprotein acceptor to apo C.
D000418:Albumins / Q000378:metabolism; D000818:Animals; D001053:Apolipoproteins / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008071:Lipoprotein Lipase / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism*; D008297:Male; D008892:Milk / Q000201:enzymology; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D014280:Triglycerides / Q000378:metabolism
D000418:Albumins; D001053:Apolipoproteins; D005230:Fatty Acids, Nonesterified; D008079:Lipoproteins, VLDL; D010743:Phospholipids; D014280:Triglycerides; D002784:Cholesterol; D008071:Lipoprotein Lipase