EXPERIMENTAL FIGURE 6-31 Gene and protein tagging facilitate cellular localization of proteins expressed from cloned genes. In this experiment, the gene encoding a chemical odorant receptor, Odr10, of C. elegans was fused to the gene encoding green fluorescent protein (GFP). (a) A promoter-fusion was generated by linking just the promoter of Odr10 to the coding sequence for GFP. The result is that GFP is expressed in the cytoplasm of the same specific sensory neurons in the head of C. elegans where Odr10 is expressed. (b) A protein-fusion was constructed by linking GFP to the end of the full-length Odr10 coding sequence. In this case, the Odr10-GFP fusion protein is targeted to the membrane at the tip of the sensory neurons and is apparent only at the distal end of the sensory cilia. The observed distribution can be inferred to reflect the normal location of Odr10 protein in specific neurons. Because the promoter-fusion shown in (a) lacks the Odr10 localization sequences, the expressed GFP fills the entire cell cytoplasm rather than being localized just to the distal tip of the sensory cilia.

[Courtesy Ashish Maurya.]