ABSTRACT
The molecular analysis of mammalian genomes aims to provide insights into gene organization and function that will assist efforts to isolate genes important in human disease. This chapter discusses a specific application of retroviral insertional mutagenesis for the isolation of transcriptionally active mammalian genes. The activating mechanism of gene trap vectors is dependent on the availability of splice acceptor sequences inserted upstream of the reporter gene. Chemical mutagenesis has provided a useful means for the analysis of biochemical pathways. Gene trap integrations are expected to mimic faithfully the expression pattern of the disrupted endogenous gene and can thus identify genes that are regulated at the transcriptional level by any biological stimulus. Large collections of clones can be selected: against expression, to obtain clones with integrations in transcriptionally inactive sites of the genome including silent genes, or for functional gene fusions to obtain clones with integrations in expressed genes.
