Trams E G, Lauter C J, Salem N, Heine U
Biochim Biophys Acta. 1981 Jul 6;645(1):63-70. doi: 10.1016/0005-2736(81)90512-5.
Cultures from various normal and neoplastic cell lines exfoliated vesicles with 5'-nucleotidase activity which reflected the ecto-enzyme activity of the parent monolayer culture. The ratio of 5'-nucleotidase to ATPase activity in the microvesicles indicated that cellular ecto-ATPase was conserved in the exfoliative process. Phospholipids of the microvesicles contained significantly increased amounts of sphingomyelin and total polyunsaturated fatty acids. It was concluded that the shedded vesicles constituted a select portion of the plasma membrane. Examination by electron microscopy showed the vesicles had an average diameter of 500 to 1000 nm and often contained a second population of vesicles about 40 nm in diameter. As much as 70% of the plasma membrane ecto-5'-nucleotidase activity of a culture was released into the medium over a 24-h period. Phosphoesterhydrolases from C-6 glioma or N-18 neuroblastoma microvesicles dephosphorylated cell surface constituents when in contact with monolayer cultures. Exfoliated membrane vesicles may serve a physiologic function; it is proposed that they be referred to as exosomes.
来自各种正常和肿瘤细胞系的培养物可脱落具有5'-核苷酸酶活性的囊泡，该活性反映了亲代单层培养物的胞外酶活性。微囊泡中5'-核苷酸酶与ATP酶活性的比值表明，细胞胞外ATP酶在脱落过程中得以保留。微囊泡的磷脂中鞘磷脂和总多不饱和脂肪酸的含量显著增加。得出的结论是，脱落的囊泡构成了质膜的一个特定部分。电子显微镜检查显示，这些囊泡的平均直径为500至1000纳米，且常常包含一群直径约40纳米的小囊泡。在24小时内，培养物中高达70%的质膜胞外5'-核苷酸酶活性被释放到培养基中。来自C-6胶质瘤或N-18神经母细胞瘤微囊泡的磷酸酯水解酶在与单层培养物接触时会使细胞表面成分去磷酸化。脱落的膜囊泡可能具有生理功能；有人提议将它们称为外泌体。
