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Battelli MG Musiani S Buonamici L Santi S Riccio M Maraldi NM Girbés T Stirpe F 《Cellular and molecular life sciences : CMLS》2004,61(15):1975-1984
Among two-chain ribosome-inactivating proteins (RIPs), volkensin is the most toxic to cells and animals, and
is retrogradely axonally transported in the rat central nervous system, being an effective suicide transport
agent. Here we studied the binding, endocytosis, intracellular routeing, degradation and exocytosis of this RIP.
The interaction of volkensin with HeLa cells was compared to that of nigrin b, as an example of a type 2 RIP with
low toxicity, and of ricin, as a reference toxin. Nigrin b and volkensin bound to cells with comparable affinity
(approx. 10-10 M) and had a similar number of binding sites (2 × 105/cell),
two-log lower than that reported for ricin. The cellular uptake of volkensin was lower than that reported for
nigrin b and ricin. Confocal microscopy showed the rapid localization of volkensin in the Golgi stacks with a
perinuclear localization similar to that of ricin, while nigrin b was distributed between cytoplasmic dots and
the Golgi compartment. Consistently, brefeldin A, which disrupts the Golgi apparatus, protected cells from the
inhibition of protein synthesis by volkensin or ricin, whereas it was ineffective in the case of nigrin b. Of the
cell-released RIPs, 57% of volkensin and only 5% of ricin were active, whilst exocytosed nigrin b was totally
inactive. Despite the low binding to, and uptake by, cells, the high cytotoxicity of volkensin may depend on (i)
routeing to the Golgi apparatus, (ii) the low level of degradation, (iii) rapid recycling and (iv) the high
percentage of active toxin remaining after exocytosis.Received 21 April 2004; received after revision 26 May 2004; accepted 9 June 2004 相似文献
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Dynamics of proteins in Golgi membranes: comparisons between mammalian and plant cells highlighted by photobleaching techniques 总被引:5,自引:0,他引:5
In less than a decade the green fluorescent protein (GFP) has become one of the most popular tools for cell biologists for the study of dynamic processes in vivo. GFP has revolutionised the scientific approach for the study of vital organelles, such as the Golgi apparatus. As Golgi proteins can be tagged with GFP, in most cases without altering their targeting and function, it is a great substitute to conventional dyes used in the past to highlight this compartment. In this review, we cover the application of GFP and its spectral derivatives in the study of Golgi dynamics in mammalian and plant cells. In particular, we focus on the technique of selective photobleaching known as fluorescence recovery after photobleaching, which has successfully shed light on essential differences in the biology of the Golgi apparatus in mammalian and plant cells. 相似文献