THE GENE-CLUSTER CONTAINING THE LCAT GENE IS CONSERVED BETWEEN HUMAN AND PIG

A pooled DNA probe from P1 artificial chromosome clones (PACs) contain ing the human lecithin:cholesterol acyl transferase (LCAT) gene cluste r was used in fluorescence in situ hybridization (FISH) experiments as signing the genes to pig chromosome 6p13. In addition, probes derived from the coding regions in the human gene cluster were used in long ra nge mapping experiments to show that the overall structures of the hum an and porcine LCAT gene clusters are identical. Both the linear order and the close physical distance of five apparently unrelated genes ha ve been maintained throughout 90 million years of divergent evolution between human and pig. The extremely dense clustering of the genes in the LCAT gene cluster suggests that this gene organization has biologi cal significance. The conservation of the gene cluster between human a nd pig supports this suggestion.