Isolation and characterization of the major plasma apolipoproteins, A-1 and B, in the European badger, Meles meles.

Abstract

The two major apolipoproteins of badger serum, apoA-I and apoB, have been isolated and characterized. Apolipoprotein A-I was the principal protein of badger lipoproteins with density 1.063-1.21 g/ml and, in addition, was present in the lipoprotein class with density 1.006-1.063 g/ml. This apolipoprotein displayed an Mr of approximately equal to 27,000-28,000 and was polymorphic (three prominent isoproteins) on isoelectric focusing, with pI values in the range 5.38-5.55. The amino acid profile of badger apoA-I generally resembled those reported in the literature for similar proteins in dog and man. Amino terminal sequence analysis up to the 40th residue showed close homology between the badger, dog, and human proteins; badger and dog apoA-I differed only at residue 24, at which serine in the dog was substituted by glycine in the badger. Several forms of apolipoprotein B were present in badger lipoproteins with densities less than 1.063 g/ml, their distribution and apparent Mr being unaffected by the presence or absence of 1 mM PMSF during the isolation process. The components of higher Mr were essentially represented by a protein with Mr approximately equal to 530,000-550,000 (apoBH) as determined by SDS-polyacrylamide electrophoresis; this protein predominated both in lipoproteins with d 1.006-1.063 g/ml and in those with d less than 1.006 g/ml. In addition, proteins with approximate Mr values of 490,000, 450,000, and 190,000, respectively, were present as minor components. A lower Mr form (250,000, apoBL), was observed only in lipoproteins with d less than 1.006 g/ml.(ABSTRACT TRUNCATED AT 250 WORDS)