STRUCTURE OF THE HAMSTER LOW-DENSITY-LIPOPROTEIN RECEPTOR GENE

The metabolism of low density lipoprotein (LDL) in the hamster is substantially similar to that of the human. To extend the usefulness of the hamster as an experimental model, the hamster LDL receptor gene was isolated and characterized. The gene is composed of 18 exons and 17 introns which span 26 kilobases. The introns occur at precisely the same positions as those previously determined for the human LDL receptor gene. The 18 exons of the hamster gene predict an LDL receptor protein of 854 amino acids that is similar in organization and sequence to those predicted from the cDNAs of rat, rabbit, cow, and human. Within the 5'-flanking region of the hamster LDL receptor gene are three highly conserved imperfect direct repeat sequences of 16 nucleotides each that in the human gene have been demonstrated to regulate transcription. In addition, a similar arrangement of direct repeat sequences was also isolated from the 5-flanking region of the rat LDL receptor gene using the polymerase chain reaction. These results indicate a strong sequence and structural conservation of the LDL receptor among several species and further support the hamster as an experimental model for the study of human LDL-cholesterol metabolism.