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Probably the best probes to visualize the Golgi are antibodies specific for proteins that reside inside the lumen of this organelle. Several of these, such as COPII, are available commercially from many vendors.
I have had some success labeling the Golgi using fluorescently-conjugated lectins. As one of the primary functions of the Golgi is glycosylation of proteins, the Golgi apparatus and Golgi-derived vesicles may be stained using lectins specific for sugar residues present in this compartment8,9. I have found wheat germ agglutinin (WGA) to be particularly useful as it does not require any special buffer conditions. Cells may be fixed by either precipitation or cross-linking, although I have found that the GA's morphology is best preserved by aldehyde fixation. Samples should be extracted with 1% Triton X-100 for 15 minutes in order to allow access to the lectin, as well. I have used rhodamine-conjugated WGA from Vector Laboratories, which is provided as an aqueous solution at 1 mg/mL, diluted to 10 µg/mL to stain cells for one hour. If performing double labeling with antibodies, it may be wise to perform the lectin staining after staining with secondaries as IgGs are, themselves, glycosylated and simultaneous incubation my induce formation of antibody aggregates. Using rhodamine-WGA, I have been able to visualize the juxtanuclear Golgi apparatus in many cell types. In addition, small vesicles are labeled along with the plasma membrane, although not as intensely. Unfortunately, WGA also labels the serum proteins present in the growth medium that adhere to the coverslip, producing a uniform, low level of background fluorescence. This background is usually low enough that it may be eliminated from final images by manipulating their gray scale histograms or look-up tables.
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