Adams C J, Maurey K M, Storrie B
J Cell Biol. 1982 Jun;93(3):632-7. doi: 10.1083/jcb.93.3.632.
The extent of exocytosis of pinocytic vesicle contents was studied in suspension-cultured Chinese hamster ovary (CHO) cells using horseradish peroxidase (HRP) as a pinocytic content marker. HRP was shown to be internalized via fluid-phase pinocytosis in CHO cells. After an HRP pulse of 2.5-10 min a rapid decrease of 30-50% in cell-associated HRP activity was observed within 10-20 min at 37 degrees C. During this time the loss of cell-associated HRP was accompanied by an equivalent increase in extracellular HRP. After this rapid exocytosis of HRP, the remaining peroxidase activity decreased with a t1/2 of 6-8 h, the known lysosomal half-life of HRP. In pulse-chase experiments HRP was chased into a nonexocytic compartment. Based on cell fractionation and electron microscopic experiments, this nonexocytic compartment was identified as a lysosome and the compartment from which exocytosis occurs as a pinosome. The occurrence of pinocytic content exocytosis in cultured fibroblasts suggests that exocytosis of pinocytic vesicle contents is a general phenomenon.
利用辣根过氧化物酶（HRP）作为胞饮内容物标记物，研究了悬浮培养的中国仓鼠卵巢（CHO）细胞中胞饮小泡内容物的胞吐程度。结果表明，HRP在CHO细胞中通过液相胞饮作用被内化。在2.5 - 10分钟的HRP脉冲处理后，在37℃下10 - 20分钟内观察到细胞相关HRP活性迅速下降30 - 50%。在此期间，细胞相关HRP的损失伴随着细胞外HRP的等量增加。HRP快速胞吐后，剩余的过氧化物酶活性以6 - 8小时的t1/2下降，这是HRP已知的溶酶体半衰期。在脉冲追踪实验中，HRP被追踪到一个非胞吐区室。基于细胞分级分离和电子显微镜实验，这个非胞吐区室被鉴定为溶酶体，而发生胞吐的区室为胞饮体。培养的成纤维细胞中胞饮内容物胞吐的发生表明，胞饮小泡内容物的胞吐是一种普遍现象。
