Joseph K C, Kim S U, Stieber A, Gonatas N K
Proc Natl Acad Sci U S A. 1978 Jun;75(6):2815-9. doi: 10.1073/pnas.75.6.2815.
Cholera toxin linked covalently by glutaraldehyde to horseradish peroxidase was incubated with cultured chicken sympathetic neurons at 4 degrees. Cells were washed and brought to 37 degrees to permit endocytosis of bound toxin on plasma membranes. Massive internalization of the ligand into vesicles and cisterns of the Golgi--endoplasmic reticulum--lysosome (GERL) system was demonstrated by the cytochemical reaction for the enzyme. Surface binding and subsequent endocytosis of the cholera toxin--enzyme conjugate was inhibited when conjugate and monosialoganglioside (GM1) were simultaneously applied to cells at 4 degrees. Cholera toxin is not toxic to neurons at the levels used. These results indicate that GERL is the primary site of endocytosis of presumed complexes of cholera toxin with its plasma membrane receptor (GM1 ganglioside-containing moieties). It is suggested that, in neurons, plasma-membrane bound ligands are taken up primarily into GERL.
用戊二醛将霍乱毒素与辣根过氧化物酶共价连接，于4℃下与培养的鸡交感神经元一起孵育。细胞经洗涤后，置于37℃，以使结合在质膜上的毒素发生内吞作用。通过对该酶的细胞化学反应证明，配体大量内化进入高尔基体 - 内质网 - 溶酶体（GERL）系统的小泡和池。当在4℃下将缀合物和单唾液酸神经节苷脂（GM1）同时应用于细胞时，霍乱毒素 - 酶缀合物的表面结合及随后的内吞作用受到抑制。所用水平的霍乱毒素对神经元无毒。这些结果表明，GERL是霍乱毒素与其质膜受体（含GM1神经节苷脂部分）假定复合物的主要内吞部位。有人提出，在神经元中，质膜结合的配体主要被摄取到GERL中。
