Journal of Lipid Research, Vol. 13, 317-324, May 1972
Copyright © 1972 by Lipid Research, Inc.

Interrelationship between rat serum very low density and high density lipoproteins

Bernard Rubenstein and David Rubinstein

Department of Biochemistry, McGill University, Montreal, Quebec

An exchange of phospholipids and certain peptides among various classes of rat serum lipoproteins has been demonstrated and its nature has been investigated. [³²P]-Phospholipid from isolated VLDL, prepared in vivo, was transferred to HDL, and to a much lesser extent to LDL, in vivo and in vitro. This difference between HDL and LDL can be abolished by ultracentrifugation of the serum at d 1.21. Unlabeled VLDL acquired [³²P]phospholipid from HDL of serum. Phospholipid associated with the -lipoprotein component of VLDL exchanged more readily than that associated with the ßbeta;-lipoprotein component of VLDL. Generally, the phospholipid species exchange in proportion to their distribution in the lipoproteins.

Radioactivity from ³H-labeled protein of VLDL was transferred to HDL while HDL ³H-labeled protein in serum was transferred to VLDL during a 20-min incubation. LDL was not involved in the transfer of protein. Protein associated with the -lipoprotein component of VLDL exchanged more readily than that associated with ßbeta;-lipoprotein component. Analysis of tritiated apoproteins of VLDL and HDL by polyacrylamide gel electrophoresis revealed that three of the six peptide bands of apo-VLDL exchanged between VLDL and HDL.

The data raise the possibility that intact subunits of the VLDL and HDL are being exchanged.

Supplementary key words phospholipids • apolipoproteins • low density lipoproteins • gel electrophoresis

Submitted on May 12, 1971
Revised on August 31, 1971
Accepted on December 10, 1971

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?