Cloning and characterization of the gene for rabbit C-reactive protein

Abstract

C-reactive protein (CRP), an acute-phase plasma protein of hepatic origin in man and rabbit, is a cyclic pentamer composed of five identical nonglycosylated Mr 22 500 subunits. We have isolated both cDNA and genomic clones for rabbit CRP. These clones were used as probes to demonstrate that when CRP synthesis is increased following an acute inflammatory stimulus, there is a corresponding increase in the level of accumulated CRP mRNA. The rabbit CRP gene is 2.6 kilobases in length containing a single intron of 252 base pairs (bp) which interrupts the codon for amino acid 2 in the protein. The mRNA for CRP contains a 5'-nontranslated region of 113 bp and a 3'-nontranslated region of 1550 bp. Sequencing of the protein-coding region of the gene indicates that the primary translation product contains a 20 amino acid N-terminal signal peptide. The deduced amino acid sequence is in general agreement with the published sequence [Wang, C. M., Nguyen, N. Y., Yonaha, K., Robey, F., & Liu, T.-Y. (1982) J. Biol. Chem. 257, 13610-13615] except in the region between amino acids 63 and 73. In this region, the sequence of both cDNA and genomic clones indicates the presence of 28 amino acids not previously reported. This alteration may be the result of genetic heterogeneity or an error in the reported protein sequence.