CAPTURING GENES ENCODING MEMBRANE AND SECRETED PROTEINS IMPORTANT FORMOUSE DEVELOPMENT

A strategy based on the gene trap was developed to prescreen mouse emb ryonic stem cells for insertional mutations in genes encoding secreted and membrane-spanning proteins. The ''secretory trap'' relies on capt uring the N-terminal signal sequence of an endogenous gene to generate an active beta-galactosidase fusion protein. Insertions were found in a cadherin gene, an unc6-related laminin (netrin) gene, the sek recep tor tyrosine kinase gene, and genes encoding two receptor-linked prote in-tyrosine phosphatases, LAR and PTP kappa. Analysis of homozygous mi ce carrying insertions in LAR and PTP kappa showed that both genes wer e effectively disrupted, but neither was essential for normal embryoni c development.