Table II.

Effect of Sq on cell growth, sterol biosynthesis, and SQS activity

Sq	fwt	4-Demethylsterols			SQS Activity
nm	g	mg g−1 dwt	cpm g−1 dwt	%	nmol h−1 mg−1 protein
0	6.5	1.7	124,050	100	10.5 ± 1
50	5.0	1.0	4,980	4.0	0.25 ± 0.1
75	4.2	0.8	2,550	2.0	0.20 ± 0.1
100	3.7	0.7	2,580	2.1	0.1 ± 0.1
500	3.2	0.6	540	0.4	0.1 ± 0.1

Three-day-old TBY-2 cells were treated with various concentrations (from 0 to 500 nm) of Sq for 24 h, then incubated with sodium [1-¹⁴C]acetate for 2 h just before cell harvesting. Total sterols were quantified by GC as acetate derivatives. SQS activity was measured in the presence of [1-³H]FPP and 10 μg of microsomal protein. fwt, Fresh weight; dwt, dry weight.