Wesche Jørgen
Department of Biochemistry, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, Oslo.
Int J Med Microbiol. 2002 Feb;291(6-7):517-21. doi: 10.1078/1438-4221-00161.
The plant toxin ricin binds to terminal galactose-containing cell-surface receptors. The toxin is endocytosed and transported to the Golgi apparatus. Recent evidence suggests that ricin binds to galactosylated calreticulin, which may carry the toxin from the Golgi apparatus to the endoplasmic reticulum (ER). From the ER, the ricin A fragment is translocated to the cytosol. Ricin is perceived to be a candidate for ER-associated degradation (ERAD) and is translocated through the Sec61p translocon to the cytosol. Part of the toxin is degraded by the proteasome, but a fraction of the ricin avoids degradation and inhibits protein synthesis by inactivating ribosomes, ultimately leading to cell death.
植物毒素蓖麻毒素与含末端半乳糖的细胞表面受体结合。该毒素被内吞并转运至高尔基体。最近的证据表明，蓖麻毒素与半乳糖基化的钙网蛋白结合，后者可能将毒素从高尔基体转运至内质网（ER）。从内质网，蓖麻毒素A片段被转运至细胞质溶胶。蓖麻毒素被认为是内质网相关降解（ERAD）的一个候选物，并通过Sec61p转运体转运至细胞质溶胶。部分毒素被蛋白酶体降解，但一小部分蓖麻毒素避免了降解，并通过使核糖体失活来抑制蛋白质合成，最终导致细胞死亡。
