The baboon apolipoprotein E gene: structure, expression, and linkage with the gene for apolipoprotein C-1.
To develop the baboon model for molecular genetic studies of atherosclerosis, we have cloned and sequenced the baboon apolipoprotein E (apo E) gene. The baboon apo E gene encodes the E4 isoform with respect to specific amino acid positions, suggesting that the common epsilon 3 allele is not the primal human allele. Rather than accumulating predominantly synonymous nucleotide changes, 50% of substitutions in human and baboon apo E gene coding regions cause amino acid substitutions. However, comparisons of these apo E proteins show conservation of amphipathic helices required for apo E--lipid interactions. The human and baboon apo E genes have diverged less extensively than those from rat and mouse, providing further evidence for a slowing of molecular evolution in primate species. The baboon and rhesus monkey apo E genes (intron 2) contain two Alu repeats that are absent in the human gene, indicating insertion after the divergence of human and cercopithecine lineages, but before the baboon/rhesus divergence. S1 nuclease studies show that transcription of the baboon apo E gene starts at two different positions, one of which corresponds to the human gene start site. To examine linkage of apolipoprotein genes in the baboon genome, we have used a human cDNA probe to detect apo C-I gene sequences approximately 4 kb from the 3' end of the baboon apo E gene.
Hixson
J E
JE
Department of Genetics, Southwest Foundation for Biomedical Research, San Antonio, Texas 78284.
Cox
L A
LA
Borenstein
S
S
D000595:Amino Acid Sequence; D000818:Animals; D053302:Apolipoprotein C-I; D001056:Apolipoproteins C / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D005091:Exons; D005796:Genes; D008040:Genetic Linkage; D006801:Humans; D007438:Introns; D008099:Liver / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010215:Papio / Q000235:genetics*; D051381:Rats; D013045:Species Specificity; D014158:Transcription, Genetic
D053302:Apolipoprotein C-I; D001056:Apolipoproteins C; D001057:Apolipoproteins E; D004247:DNA