Achleitner G, Zweytick D, Trotter P J, Voelker D R, Daum G
Institut für Biochemie und Lebensmittelchemie, Technische Universität Graz, Austria.
J Biol Chem. 1995 Dec 15;270(50):29836-42. doi: 10.1074/jbc.270.50.29836.
The sequence of biosynthetic steps from phosphatidylserine to phosphatidylethanolamine (via decarboxylation) and then phosphatidylcholine (via methylation) is linked to the intracellular transport of these aminoglycerophospholipids. Using a [3H]serine precursor and permeabilized yeast cells, it is possible to follow the synthesis of each of the aminoglycerophospholipids and examine the requirements for their interorganelle transport. This experimental approach reveals that in permeabilized cells newly synthesized phosphatidyl-serine is readily translocated to the locus of phosphatidylserine decarboxylase 1 in the mitochondria but not to the locus of phosphatidylserine decarboxylase 2 in the Golgi and vacuoles. Phosphatidylserine transport to the mitochondria is ATP independent and exhibits no requirements for cytosolic factors. The phosphatidylethanolamine formed in the mitochondria is exported to the locus of the methyltransferases (principally the endoplasmic reticulum) and converted to phosphatidylcholine. The export of phosphatidylethanolamine requires ATP but not any other cytosolic factors and is not obligately coupled to methyltransferase activity. The above described lipid transport reactions also occur in permeabilized cells that have been disrupted by homogenization, indicating that the processes are extremely efficient and may be dependent upon stable structural elements between organelles.
从磷脂酰丝氨酸到磷脂酰乙醇胺（通过脱羧作用）再到磷脂酰胆碱（通过甲基化作用）的生物合成步骤序列与这些氨基甘油磷脂的细胞内运输相关联。使用[3H]丝氨酸前体和透化酵母细胞，可以追踪每种氨基甘油磷脂的合成，并研究其细胞器间运输的需求。这种实验方法表明，在透化细胞中，新合成的磷脂酰丝氨酸很容易转运到线粒体中磷脂酰丝氨酸脱羧酶1的位点，但不会转运到高尔基体和液泡中磷脂酰丝氨酸脱羧酶2的位点。磷脂酰丝氨酸向线粒体的运输不依赖ATP，且对胞质因子没有需求。在线粒体中形成的磷脂酰乙醇胺被输出到甲基转移酶的位点（主要是内质网）并转化为磷脂酰胆碱。磷脂酰乙醇胺的输出需要ATP，但不需要任何其他胞质因子，且并不必然与甲基转移酶活性相关联。上述脂质运输反应也发生在通过匀浆破坏的透化细胞中，这表明这些过程极其高效，并且可能依赖于细胞器之间稳定的结构元件。
