Sequence of horse (Equus caballus) apoA-II. Another example of a dimer forming apolipoprotein.
Apolipoprotein A-II, the second major apolipoprotein of human HDL, also has been observed in a variety of mammals; however, it is either present in trace amounts or absent in other mammals. In humans and chimpanzee, and probably in other great apes, apoA-II with a cysteine at residue 6 is able to form a homodimer. In other primates as well as other mammals, apoA-II, lacking a cysteine residue, is monomeric. However, horse HDL has been reported to contain dimeric apoA-II that following reduction forms monomers. In this report, we extend these observations by reporting on the first complete sequence for a horse apolipoprotein and by demonstrating that horse apoA-II also contains a cysteine residue at position 6. Both the intact protein and its enzymatic fragments were analyzed by chemical sequence analysis and time-of-flight MALDI-MS (matrix assisted laser desorption ionization mass spectrometry). We also obtained molecular mass data on dimeric and monomeric apoA-II using electrospray-ionization mass spectrometry (ESI-MS). The data are compared with other mammalian sequences of apoA-II and are discussed in terms of resulting similarities and variations in the primary sequences.
Puppione
Donald L
DL
Boyer Hall, 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
Fischer
Wolfgang H
WH
Park
Minkyu
M
Whitelegge
Julian P
JP
Schumaker
Verne N
VN
Golfeiz
Shoulamit
S
MacDonald
Melinda H
MH
D000595:Amino Acid Sequence; D000818:Animals; D016633:Apolipoprotein A-II / Q000378:metabolism*; D019281:Dimerization; D006736:Horses; D006801:Humans; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D016633:Apolipoprotein A-II