Comparison of the human,canine and swine E apoproteins

A comparative study of the E apoprotein isolated from the d<1.02 lipoproteins of human, canine and swine plasma revealed that the various apo-E preparations had similar molecular weights (37,000–39,000) and had similar amino acid compositions in that glutamic acid, alanine, leucine and arginine were present in high concentrations. The various preparations showed partial immunochemical cross-reactivity, demonstrating significant sequence homology between the species. However, determination of the amino-terminal amino acid sequence by automated Edman degradation showed each apo-E was different, demonstrating that the amino-terminal portion of the E apoprotein was a variable region of this protein.