Braun M, Waheed A, von Figura K
Institut für Biochemie II, Göttingen, FRG.
EMBO J. 1989 Dec 1;8(12):3633-40. doi: 10.1002/j.1460-2075.1989.tb08537.x.
Lysosomal acid phosphatase (LAP) is transported as a transmembrane protein to dense lysosomes. The pathway of LAP to lysosomes includes the passage through the plasma membrane. LAP is transported from the trans-Golgi to the cell surface with a half-time of less than 10 min. Cell surface LAP is rapidly internalized. Most of the internalized LAP is transported back to the cell surface. On average, each LAP molecule cycles greater than 15 times between the cell surface and the endosomes before it is transferred to dense lysosomes. At equilibrium approximately 4 times more LAP precursor is present in endosomes than at the cell surface. Exposing cells to reduced temperature or weak bases such as NH4Cl, chloroquine and primaquine decreases the steady-state concentration of LAP at the cell surface. The recycling pathway is operative at greater than or equal to 20 degrees C and does not include passage of the Golgi/trans-Golgi network. LAP is transferred with a half-time of 5-6 h from the plasma membrane/endosome pool to dense lysosomes, from where it does not recycle to the endosome/plasma membrane pool at a measurable rate.
溶酶体酸性磷酸酶（LAP）作为一种跨膜蛋白被转运至致密溶酶体。LAP至溶酶体的途径包括穿过质膜。LAP从反式高尔基体转运至细胞表面的半衰期不到10分钟。细胞表面的LAP会迅速内化。大部分内化的LAP会被转运回细胞表面。平均而言，每个LAP分子在被转运至致密溶酶体之前，会在细胞表面和内体之间循环超过15次。在平衡状态下，内体中存在的LAP前体比细胞表面大约多4倍。将细胞暴露于低温或弱碱如氯化铵、氯喹和伯氨喹会降低细胞表面LAP的稳态浓度。循环途径在大于或等于20摄氏度时起作用，且不包括高尔基体/反式高尔基体网络的通过。LAP从质膜/内体池转运至致密溶酶体的半衰期为5 - 6小时，从致密溶酶体它不会以可测量的速率再循环至内体/质膜池。
