Rat apolipoprotein C-II lacks the conserved site for proteolytic cleavage of the pro-form.
Apolipoprotein C-II (apoC-II) plays a critical role in the metabolism of plasma lipoproteins as an activator for lipoprotein lipase. Human apoC-II consists of 79 amino acid residues (pro-apoC-II). A minor fraction is converted to a mature form by cleavage at the site QQDE releasing the 6 amino-terminal residues. We have cloned and sequenced the cDNA for rat apoC-II from a liver cDNA library using human apoC-II cDNA as a probe. The cDNA encodes a protein of 97 amino acid residues including a signal peptide of 22 amino acid residues. There is approximately 60% similarity between the deduced amino acid sequence of rat apoC-II and other apoC-II sequences presently known (human, monkey, dog, cow, and guinea pig). Compared to these, rat apoC-II is one residue shorter at the carboxyl terminus. Furthermore, there is a deletion of 3 amino acid residues (PQQ) in the highly conserved cleavage site where processing from pro- to mature apoC-II occurs in other species. Accordingly, rat apoC-II isolated from plasma was mainly in the pro-form. Northern blot analyses indicated that rat apoC-II is expressed both in liver and in small intestine.
Andersson
Y
Y
Department of Medical Biochemistry and Biophysics, University of Umeå, Sweden.
Thelander
L
L
Bengtsson-Olivecrona
G
G
D000595:Amino Acid Sequence; D000818:Animals; D053304:Apolipoprotein C-II; D001056:Apolipoproteins C / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004247:DNA; D006801:Humans; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D016415:Sequence Alignment
D053304:Apolipoprotein C-II; D001056:Apolipoproteins C; D011498:Protein Precursors; D004247:DNA