title: Amino acid sequence of rat apolipoprotein A-II deduced from the nucleotide sequence of cloned cDNA.
abstract: 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)
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016633:Apolipoprotein A-II; D001054:Apolipoproteins A / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D016633:Apolipoprotein A-II; D001054:Apolipoproteins A; D012333:RNA, Messenger; D004247:DNA