Ramgopal M, Zundel M, Bloch K
James Bryant Conant Laboratories, Department of Chemistry, Harvard University, Cambridge, MA 02138.
J Lipid Res. 1990 Apr;31(4):653-8.
Cells of the yeast sterol auxotroph GL7 were grown on either ergosterol or cholesterol to mid-logarithmic phase and total membrane fractions prepared. Activities of phospholipid biosynthetic enzymes in the two cell types were determined. The rates of phosphatidyl-ethanolamine-phosphatidyl-choline-N-methyl transferase and acyl-CoA-alpha-glycerol-3-phosphate transcylase were significantly greater in ergosterol-grown than in cholesterol-grown cells. These reactions were also inhibited by the polyene antibiotic filipin. By contrast the activities of long-chain fatty acyl-CoA synthetase, CTP-phosphatidate-cytidyl transferase, phosphatidylserine decarboxylase and of phosphatidylinositol synthetase were identical in the two (ergosterol and cholesterol) cultures and unaffected by filipin. The ergosterol effect on phosphatidyl-ethanolamine N-methyl transferase was greatest in cells harvested in early log phase, intermediate in the mid-log phase cells, and not significant in stationary phase cells.
酵母甾醇营养缺陷型GL7细胞在麦角固醇或胆固醇上生长至对数中期，并制备总膜组分。测定了两种细胞类型中磷脂生物合成酶的活性。在以麦角固醇生长的细胞中，磷脂酰乙醇胺-磷脂酰胆碱-N-甲基转移酶和酰基辅酶A-α-甘油-3-磷酸转酰酶的活性显著高于以胆固醇生长的细胞。这些反应也受到多烯抗生素制霉菌素的抑制。相比之下，长链脂肪酰基辅酶A合成酶、CTP-磷脂酸-胞苷转移酶、磷脂酰丝氨酸脱羧酶和磷脂酰肌醇合成酶的活性在两种（麦角固醇和胆固醇）培养物中相同，且不受制霉菌素影响。麦角固醇对磷脂酰乙醇胺N-甲基转移酶的影响在对数早期收获的细胞中最大，在对数中期细胞中居中，在稳定期细胞中不显著。
