THE EXON TRAPPING ASSAY PARTLY DISCRIMINATES AGAINST ALTERNATIVELY SPLICED EXONS

A cosmid containing eight exons of the gene coding for the microtubule -associated tau protein was subjected to the exon trapping assay. All the constitutive exons contained in the cosmid (4, 5, 7 and 9) were ef ficiently captured regardless of size. Of the four alternatively splic ed exons, three (3, 4A and 8) were not isolated by the assay, but the behavior of exon 6 depended on the identity of its flanking exons.