Homework Question:

In enhancer trapping, reporter transgenes are integrated randomly into the fly genome and their expression identifies enhancers and thereby genes expressed in particular patterns. In mice, a similar technique for gene identification is employed called “gene trapping.” In gene trapping, an exon encoding a reporter protein such as GFP (see below) is integrated into random locations in ES cell chromosomes. (When DNA constructs are introduced into mouse ES cells, most recombination events are into random sites; homologous recombination is relatively rare.) ES cell lines with randomly integrated transgenes are used to generate mice.

Where in the genome must a gene trapping construct integrate in order for ES cells to express GFP?

Answer:

My Question:

Why can't the construct simply be knocked into the coding DNA sequence of the mouse genome? Why does it have to be integrated into an intron?

Homework Question:

In enhancer trapping, reporter transgenes are integrated randomly into the fly genome and their expression identifies enhancers and thereby genes expressed in particular patterns. In mice, a similar technique for gene identification is employed called “gene trapping.” In gene trapping, an exon encoding a reporter protein such as GFP (see below) is integrated into random locations in ES cell chromosomes (when DNA constructs are introduced into mouse ES cells, most recombination events are into random sites; homologous recombination is relatively rare). ES cell lines with randomly integrated transgenes are used to generate mice.

Where in the genome must a gene trapping construct integrate in order for ES cells to express GFP?

Answer:

My Question:

Why can't the construct simply be knocked into the coding DNA sequence of the mouse genome? Why does it have to be integrated into an intron?