A new gene trap construct enriching for insertion events near the 5 ' end of genes

The gene trap approach is based on the integration of a gene trap vector in to the genome. This can be done either by electroporation of a plasmid cons truct or by infection with a viral vector. Commonly used viral gene trap ve ctors have been shown to select for integrations near the 5' end of genes. To date, no plasmid vector with a similar tendency has been reported. In th is paper we describe a new plasmid vector, pKC199 beta geo. This vector con tained a short splice acceptor fragment from the Hoxc9 gene, a full length lacZ gene, including an ATG, and a reduced activity, mutant neomycin phosph otransferase gene as a selectable marker. This vector enriched the populati on of trapped genes in our gene trap screen for insertion events in the 5' end of genes. In the two cases examined the beta -galactosidase activity pa ttern accurately reflected the endogenous promotor activity.