Protein G-gold complex: comparative evaluation with protein A-gold for high-resolution immunocytochemistry.
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.
D000681:Amylases / Q000378:metabolism; D000818:Animals; D002451:Cell Compartmentation; D004247:DNA / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods*; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000378:metabolism; D008854:Microscopy, Electron; D009419:Nerve Tissue Proteins; D010179:Pancreas / Q000201:enzymology; D012313:RNA / Q000378:metabolism; D051381:Rats; D013045:Species Specificity; D013205:Staphylococcal Protein A
C029152:G-substrate; D007328:Insulin; D009419:Nerve Tissue Proteins; D013205:Staphylococcal Protein A; D012313:RNA; D004247:DNA; D000681:Amylases