Lam W K, Beatty M F, Hahn S, Djerassi C
Department of Chemistry, Stanford University, California 94305.
Biochemistry. 1991 Jan 15;30(2):372-7. doi: 10.1021/bi00216a010.
Sponges are unique in regard to membrane phospholipid composition. Features virtually without parallel in other organisms are the predominance of the C26-C30 polyenoic acids (demospongic acids) in the phosphatidylethanolamines (PE) and the attachment of identical acyl groups to the glycerol moiety. The biosynthesis and disposition of these unusual phospholipids were followed in the marine sponge Microciona prolifera where PE ( delta 5,9-26:2, delta 5,9-26:2) is a major molecular species. Incorporation experiments with radiolabeled fatty acids, bases, and intact phospholipids revealed the de novo biosynthesis of the two major phosphatides, phosphatidylethanolamines (PE) and phosphatidylcholines (PC), via the cytidine pathway as in higher animals, with ethanolamine selectively incorporated into PE( delta 5,9-26:2, delta 5,9-26:2). Methylation of PE and random acyl chain migration across different phospholipid classes were marginal, but the exchange of PC for PE, apparently mediated by the action of phospholipase, was indicated after uptake of the unnatural PC( delta 9-27:1, delta 9-26:1). The present study demonstrates in the most primitive multicellular animals a phospholipid metabolic pattern similar to that in higher organisms, with unique acyl and phosphoethanolamine transferases apparently involved in the biosynthesis of the (demospongic) di-C26-acyl-PE molecular species.
海绵在膜磷脂组成方面独具特色。在磷脂酰乙醇胺（PE）中C26 - C30多烯酸（海绵酸）占主导地位，以及相同的酰基连接到甘油部分，这些特征在其他生物中几乎没有类似情况。在海洋海绵多孔海绵属中追踪了这些异常磷脂的生物合成和分布情况，其中PE（δ5,9 - 26:2，δ5,9 - 26:2）是主要的分子种类。用放射性标记的脂肪酸、碱基和完整磷脂进行的掺入实验表明，这两种主要磷脂，即磷脂酰乙醇胺（PE）和磷脂酰胆碱（PC），通过与高等动物相同的胞苷途径从头合成，乙醇胺选择性地掺入到PE（δ5,9 - 26:2，δ5,9 - 26:2）中。PE的甲基化以及不同磷脂类之间随机的酰基链迁移作用微弱，但在摄取非天然PC（δ9 - 27:1，δ9 - 26:1）后，表明存在明显由磷脂酶作用介导的PC与PE的交换。本研究在最原始的多细胞动物中证明了一种与高等生物相似的磷脂代谢模式，其中独特的酰基和磷酸乙醇胺转移酶显然参与了（海绵）二C26 - 酰基 - PE分子种类的生物合成。
