Protein G-gold complex: comparative evaluation with protein A-gold for high-resolution immunocytochemistry.

Abstract

We combined the protein G-gold complex with several polyclonal and monoclonal antibodies for localization of various antigenic sites. The labelings were compared with those obtained using the protein A-gold complex. The results from either the immunodot experiment or immunoelectron microscopy have demonstrated that, for rabbit and guinea pig antibodies, both protein G-gold and protein A-gold complexes label several different specific antibodies with similar efficiency. However, with antibodies raised in goats or in mice, and particularly with mouse monoclonal antibodies, protein G-gold yielded intense and specific labeling, whereas protein A-gold yielded intense and specific labeling, whereas protein A-gold was very variable; it either gave weaker signals or failed to reveal any specific site or, as with one monoclonal, both protein G and protein A gave similar results. The higher affinity and versatility of protein G over protein A, established by the immunochemical approach, was confirmed by immunocytochemistry. Because of its enhanced reactivity with monoclonal antibodies and its broader affinity for polyclonal antibodies, protein G-gold complex appears to be a better and more versatile probe for high-resolution immunocytochemistry.

Preparation and use of recombinant protein G—gold complexes as markers in double labelling immunocytochemistry

“…Our quantitative results with the RPGG support the conclusions of Bendayan (1987) and Bendayan & Garzon (1988), using protein G isolated from a human 10.3" +1.4 3.5**+0.6 5.9 +1.5…”

Functional and Structural Differences among Proplastids, as Seen by Immunogold Staining and Electron Microscopy

“…Seven plumules of 2 mm in length were removed from the seeds and fixed immediately in 0.05 M cacodylate buffer (pH 7.4), that contained 4% paraformaldehyde, 0.25% glutaraldehyde, and 0.06 M sucrose for 5 h at O°C and then for 1 h at 22°C. 24 ) Washing was done twice in 0.05 M cacodylate buffer (pH 7.4) that contained 0.06 M sucrose for 10 min at 22°C, and samples were stored in 20ml of the same solution overnight at 4°C.…”

A novel colloidal gold immunochromatography assay strip for the diagnosis of schistosomiasis japonica in domestic animals

“…In addition, staphylococcal protein A (SPA) conjugated with colloidal gold has been commonly used in recent times. Nevertheless, when compared with SPA, streptococcal protein G (SPG) has a higher affinity for IgG binding and a wider application [9]. …”