Journal of Lipid Research, Vol 27, 706-712, Copyright © 1986 by Lipid Research, Inc.
Amino acid sequence of rat apolipoprotein A-II deduced from the nucleotide sequence of cloned cDNA
M Nagashima, G Morris, G Howlett, N Fidge and G Schreiber
A rat apolipoprotein A-II cDNA clone was isolated from a rat liver cDNA
library by in situ hybridization of bacteriophage plaques using a 32P-
labeled human apoA-II cDNA as a probe. The cDNA insert from this clone was
characterized by DNA sequencing. The amino acid composition derived from
the DNA sequence data matched well with that of rat apoA-II reported
earlier (Herbert et al. 1974. J. Biol Chem. 249: 5718-5724), indicating
that the cDNA insert coded for rat apoA-II. Further evidence was provided
by a comparison of the amino acid sequence of rat apoA-II obtained here
with that of human apoA-II (Brewer et al. 1972. Proc. Natl. Acad. Sci. USA.
69: 1304-1308). While the rat apoA-II cDNA insert did not code for the
entire presegment, it had the same COOH-terminal residues of the presegment
as well as the same prosegment (Ala-Leu-Val- Arg-Arg) as in human
preproapoA-II, suggesting that rat apoA-II was also synthesized initially
as preproapoA-II. Mature rat apoA-II contains 79 amino acids. Residue 6 of
mature rat apoA-II is Asp, while it is Cys in human apoA-II, and this would
account for the absence of dimeric forms of rat apoA-II in plasma. While
the overall amino acid sequence homology between rat and human apoA-II is
about 50%, the amphipathic alpha-helical structures, which are responsible
for lipid- binding, seem to be conserved in the two proteins. The size of
rat apoA- II mRNA was estimated to be about 600 nucleotides.(ABSTRACT
TRUNCATED AT 250 WORDS)
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