J L Gaylor
Johnson & Johnson
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Featured researches published by J L Gaylor.
Biochimica et Biophysica Acta | 1995
Chap-Ki Kim; Kye-Im Jeon; Dong-Min Lim; Tae-Neung Johng; James M. Trzaskos; J L Gaylor; Young-Ki Paik
We have previously characterized the membrane-bound sterol 14-reductase (14-reductase) that catalyzes anaerobically NADPH-dependent reduction of the 14-double bond of delta 8,14-diene or delta 7,14-diene sterols that are sterol intermediates in cholesterol biosynthesis in mammals (Paik et al. (1984) J. Biol. Chem. 259, 13413-13423). To elucidate the regulatory mechanism as well as molecular characteristics of the 14-reductase, we extended our investigation on the consequences of alteration of the enzymic activity under various physiological conditions. The enzymic activity of rat hepatic sterol 14-reductase was induced more than 11-fold by feeding 5% cholestyramine plus 0.1% lovastatin (the CL-diet) for 7 days but was severely suppressed by feeding 5% cholesterol or 0.01% AY-9944 (an inhibitor of 14-reductase) for the same period. The increase or decrease in the 14-reductase activity also parallels the same change in the cholesterol synthetic rate in hepatocytes from rats that had been fed either the CL-diet or 0.01% AY-9944. In vitro inhibition studies revealed that AY-9944 acts as a competitive inhibitor of the 14-reductase (Ki = 0.26 microM). A diurnal variation was observed for the 14-reductase with peak activity near the middle of the dark cycle (10 p.m.), which was abolished by administration of cycloheximide. With induced enzyme conditions 14-reductase has been further purified with chromatographic procedures to near homogeneity. Purified 14-reductase appears to be a M(r) = 70,000 protein that is composed of two equally-sized subunits having a M(r) = 38,000. All properties of the purified 14-reductase suggest that the solubilized enzyme is the principal 14-reductase of microsomes. Taken together, our results provide the first evidence in support of a previously unknown regulatory role for the 14-reductase in the overall cholesterol synthetic pathway.
Journal of Biological Chemistry | 1986
James M. Trzaskos; Sumio Kawata; J L Gaylor
Journal of Biological Chemistry | 1984
James M. Trzaskos; W D Bowen; A Shafiee; R T Fischer; J L Gaylor
Journal of Biological Chemistry | 1986
Young-Ki Paik; J T Billheimer; R L Magolda; J L Gaylor
Journal of Biological Chemistry | 1985
Sumio Kawata; James M. Trzaskos; J L Gaylor
Journal of Lipid Research | 1989
Robert Fischer; Paul R. Johnson; Soo S. Ko; Ronald L. Magolda; J L Gaylor; James M. Trzaskos
Journal of Biological Chemistry | 1984
Young-Ki Paik; James M. Trzaskos; A Shafiee; J L Gaylor
Journal of Lipid Research | 1986
A Shafiee; James M. Trzaskos; Young-Ki Paik; J L Gaylor
Journal of Biological Chemistry | 1993
James M. Trzaskos; Ronald L. Magolda; Margaret F. Favata; R T Fischer; P R Johnson; H W Chen; S S Ko; D A Leonard; J L Gaylor
Biochemistry | 1995
James M. Trzaskos; Soo S. Ko; Ronald L. Magolda; Margaret F. Favata; Robert Fischer; Paul R. Johnson; J L Gaylor