Kawasaki S, Ramgopal M, Chin J, Bloch K
Proc Natl Acad Sci U S A. 1985 Sep;82(17):5715-9. doi: 10.1073/pnas.82.17.5715.
The relatively slow growth rate of the yeast mutant GL7, a sterol auxotroph, on medium containing cholesterol is markedly accelerated by supplementation with small amounts of ergosterol. Under these conditions (sterol synergism) cellular phospholipid synthesis is enhanced. We now find that one of the ergosterol-stimulated processes is the methylation of phosphatidylethanolamine to phosphatidylcholine. This is shown by comparing methyltransferase activities of membrane preparations derived from cells grown on either ergosterol, cholesterol, or the synergistic sterol pair. Incorporation of 32P from [gamma-32P]ATP into the yeast membranes is rapid and greater when ergosterol-grown cells rather than cholesterol-grown cells are the source of membranes.
酵母突变体GL7是一种甾醇营养缺陷型,在含有胆固醇的培养基上生长相对缓慢,而添加少量麦角固醇可显著加速其生长。在这些条件下(甾醇协同作用),细胞磷脂合成增强。我们现在发现,麦角固醇刺激的过程之一是磷脂酰乙醇胺甲基化为磷脂酰胆碱。通过比较从在麦角固醇、胆固醇或协同甾醇对中生长的细胞获得的膜制剂的甲基转移酶活性可以证明这一点。当以麦角固醇生长的细胞而非胆固醇生长的细胞作为膜的来源时,[γ-32P]ATP中的32P快速掺入酵母膜且掺入量更多。