title: Mass spectral analysis of pig (Sus scrofa) apo HDL: Identification of pig apoA-II, a dimeric apolipoprotein.
abstract: Comparative studies of mammalian high density lipoproteins have clearly indicated that the major apolipoprotein is apoA-I and in some mammals apoA-II is the second major apolipoprotein. However, in pigs, apoA-II has been considered to be either present in trace amounts or absent. Recently, cDNA sequences for pigs A-II have been entered into the database. Translation of these sequences revealed that pig A-II consisted of 77 amino acids and that a cysteine residue was at residue 6. The A-II of three other mammals, chimpanzees, horses and humans, also has a cysteine residue at this position. As a result of a disulfide bond formed between monomers, the A-II in each of these cases circulates as a homodimer. Using electrospray-ionization mass spectrometry (ESI-MS), we obtained molecular mass data demonstrating that dimeric apoA-II is also present in pig plasma. In addition to being the first to report on the presence of apoA-II in pig plasma, we also obtained values for the molecular masses of apoA-I, apoC-III, apoD and serum amyloid A protein.
authors.affiliation: The Molecular Biology Institute and The Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA. puppione@chem.ucla.edu
authors.forename: Donald L
authors.initials: DL
authors.lastname: Puppione
authors.forename: Julian P
authors.initials: JP
authors.lastname: Whitelegge
authors.forename: Lang M
authors.initials: LM
authors.lastname: Yam
authors.forename: Verne N
authors.initials: VN
authors.lastname: Schumaker
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016632:Apolipoprotein A-I / Q000097:blood / Q000737:chemistry; D016633:Apolipoprotein A-II / Q000097:blood / Q000737:chemistry*; D001053:Apolipoproteins / Q000097:blood / Q000737:chemistry; D053399:Apolipoproteins D; D003545:Cysteine / Q000737:chemistry; D019281:Dimerization; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood / Q000302:isolation & purification; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D000685:Serum Amyloid A Protein / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D034421:Sus scrofa
chemical_list: D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; D001053:Apolipoproteins; D053399:Apolipoproteins D; D008075:Lipoproteins, HDL; D010446:Peptide Fragments; D000685:Serum Amyloid A Protein; D003545:Cysteine