The primary structure of apolipoprotein A-I from rabbit high-density lipoprotein.
The amino acid sequence of rabbit apolipoprotein A-I (apo A-I) has been determined by degradation and alignment of two overlapping sets of peptides obtained from tryptic and staphylococcal digestions. All of the peptides of rabbit apo A-I resulting from digestion by staphylococcal protease were isolated and sequenced except residues 33-37. A digestion with trypsin was employed to find overlapping and missing peptides. The N-terminus of rabbit apo A-I was confirmed by sequencing the intact protein up to 20 residues while the C-terminus was identified through its homology with human apo A-I. The protein contains 241 residues in its single chain. Its primary structure is highly homologous to the reported canine apo A-I (80%) and human apo A-I (78%), but exhibits less similarity with rat apo A-I (60%). Like human apo A-I, rabbit apo A-I contains very little histidine (2) and methionine (1); it does however have two residues of isoleucine. Based on a comparison of the hydrophobic-hydrophilic character of apo A-I residues with that of the two synthetic peptides that activated lecithin: cholesterol acyltransferase (Pownall et al. and Yokoyama et al.), we found that the five segments with the highest corresponding homologies on the protein are located within the N-terminal half. This suggests that the N-terminal half of apo A-I contains the major portion of regions activating lecithin: cholesterol acyltransferase.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000032:analysis*; D010450:Endopeptidases; D006868:Hydrolysis; D008666:Metalloendopeptidases; D010446:Peptide Fragments / Q000032:analysis; D011817:Rabbits; D014357:Trypsin
D000596:Amino Acids; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D010446:Peptide Fragments; D010450:Endopeptidases; D014357:Trypsin; D008666:Metalloendopeptidases; C022653:auR protein, Staphylococcus aureus