Journal of Lipid Research, Vol 25, 348-360, Copyright © 1984 by Lipid Research, Inc.
Processing of rat liver apoprotein E primary translation product
CA Reardon, RV Hay, JI Gordon and GS Getz
The primary translation product of rat liver apoE mRNA was isolated from
wheat germ cell-free translation systems. Plasma apoE and the primary
translation product migrated similarly on SDS-polyacrylamide gels, had
similar partial proteolytic peptide maps, and bound to and coeluted from
heparin-Sepharose columns. Comparison of the partial amino acid sequence of
the primary translation product with the amino- terminal sequence of plasma
apoE indicated that rat apoE is initially synthesized with an 18 amino acid
amino-terminal extension. This entire segment was removed cotranslationally
by canine microsomes possessing signal peptidase activity. The
microsome-processed translation product did not contain an endoglycosidase
H-sensitive oligosaccharide, suggesting that rat apoE is O-glycosylated.