Apolipoprotein B-100: conservation of lipid-associating amphipathic secondary structural motifs in nine species of vertebrates.

Development of a computer program called LOCATE allowed us to show that human apolipoprotein B-100 is composed of five domains, NH2-alpha1-beta1-alpha2-beta2-alpha3-COOH, enriched, alternately, in amphipathic alpha helixes and amphipathic beta strands. Using updated versions of this program, here we compare the complete sequence of human apolipoprotein B-100 with partial sequences from eight additional species of vertebrates (chicken, frog, hamster, monkey, mouse, pig, rat, and rabbit). The lipid-associating amphipathic alpha helixes cluster in domains alpha2 (between residues 2075 +/- 25 and 2575 +/- 25) and alpha3 (between residues 4100 +/- 100 and 4550 +/- 50) in all species for which those regions have been sequenced but with little conservation of individual helixes. Lipid-associating amphipathic beta strands cluster in domains beta1 (approximately residues 827-2000) and beta2 (approximately residue 2571 to residue 4000 +/- 50) in all species for which these regions have been sequenced, with conservation of several individual amphipathic beta strands. Hydrophobic segments are present in apolipoprotein B-100 sequences of all nine species but the frequency of occurrence is no greater than generally found in beta sheet-containing proteins. We conclude that four alternating lipid-associating domains, -beta1-alpha2-beta2-alpha3-COOH, are common supramolecular features of apolipoprotein B-100 in nine vertebrate species.