Abstract: Methods and vectors (both DNA and retroviral) are provided for the construction of a Library of mutated cells. The Library will preferably contain mutations in essentially all genes present in the gene of the cells. The nature of the Library and the vectors allow for methods of screening for mutations in specific genes, and for gathering nucleotide sequence data from each mutated gene to provide a database of tagged gene sequences. Such a database provides a means to access the individual mutant cell clones contained in the Library. The invention includes the described Library, methods of making the same, and vectors used to construct the Library. Methods are also provided for accessing individual parts of the Library either by sequence or by pooling and screening. The invention also provides for the generation of non-human transgenic animals which are mutant for specific genes as isolated and generated from the cells of the Library.

Abstract: Novel vectors are described that incorporate, inter alia, a novel 3′ gene trap cassette that does not encode a marker conferring antibiotic resistance and which can be used to efficiently trap, mutagenize, and identify previously unknown cellular genes. Vectors incorporating the presently described 3′ gene trap cassette find particular application in gene discovery, and the production of mutated cells and animals.