PARTIAL CLONING OF CDNA FOR HAMSTER LIVER CHOLESTEROL 7-ALPHA-HYDROXYLASE

A partial cDNA clone encoding cholesterol 7alpha-hydroxylase (pHA 7alp ha-3) was isolated from a hamster liver cNDA library using rat P-450 c h7 cDNA (p 7alpha-11) as a probe. In comparison with the complete base sequence of p 7alpha-11, pHA 7alpha-3 lacked about 500 base pairs at the 5' end. Circadian rhythms of mRNA for hamster liver 3-hydroxy-3-me thylglutaryl coenzyme A reductase and cholesterol 7alpha-hydroxylase w ere investigated with cDNA clones encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase (pRed-227) and pHA 7alpha-3. Typical circadian rh ythms of mRNA for both enzymes and a time lag between the two circadia n rhythms were observed. The circadian rhythm of activity for each enz yme corresponded to that of each mRNA.