Cloning and mRNA tissue distribution of rabbit cholesteryl ester transfer protein

Abstract

The amino acid sequence of rabbit cholesteryl ester transfer protein (CETP) has been obtained from cloned cDNA and genomic sequences. The 496 amino acid rabbit CETP has an overall sequence homology of 81% compared to the 476 amino acid human CETP, with two-thirds of the amino acid substitutions being conservative. Like human CETP, rabbit CETP is extremely hydrophobic, which is consistent with its function in the transfer of neutral lipids. The data implies extensive structural similarity between rabbit and human CETP. Rabbit CETP mRNA is estimated to be 2.2 kilobases in size, 300 nucleotides longer than the corresponding human mRNA, and contains the unusual polyadenylation signal sequence AGTAAA. In rabbit, CETP mRNA is found mainly in the liver, with small amounts also present in adrenal glands and kidney. In contrast to human spleen, rabbit spleen does not have detectable amounts of CETP mRNA. Northern blot analysis of liver poly(A)+ RNAs revealed significant amounts of CETP message in human, rhesus, and rabbit, and undetectable levels in pig, mouse, and rat, in agreement with reported plasma levels of transfer activity.