Chapter 18, Problem 20P

One way to determine where inside a cell a protein (protein X) normally localizes is to generate a reporter gene construct containing: (i) the gene X regulatory region and coding sequences, and (ii) coding sequences for GFP fused in frame to the 3′ end of the gene X coding sequences just before the stop codon. A mouse containing such a transgene will express a hybrid protein X-GFP only in those cells in which gene X is normally expressed.

a.	The gene X-GFP fusion gene described could be generated by knocking in GFP coding sequences instead of by random insertion of a transgene. Diagram the knockin construct you could use for this purpose.
b.	What might the advantage be of the knockin strategy versus the transgene strategy?