Localization by immunofluorescence microscopy of the hnRNP L protein on the lampbrush chro- 
mosomes of the North American newt Notophthalmus viridescens. The intense yellow staining 
represents a high concentration of the L protein on the landmark giant loops. This is the first 
protein localized to these mysterious segments of the chromosome. The immunofluorescence was 
performed with the monoclonal antibody 4D1 1, in collaboration with foe Gall of the Carnegie 
Institution. 
From Pinol-Roma, S., Swanson, M.S., Gall, f.G., and Dreyfuss, G. 1989. J Cell Biol 109: 
2575-2587. 
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