Abstract: An export sequence of export DNA can be identified by transforming a population of cells with a vector having a transposon that includes a structural gene encoding a detectable compound, positioned between insertion sequences. The structural gene encodes a detectable compound that, in wild-type organisms, is translated with an export peptide effective to export the compound. Since the transposon lacks DNA coding for an export sequence capable of exporting the detectable gene product, transformants that export the gene product include a DNA fusion of the transposon to export DNA from the parent cell, in a position to allow expression of the fused DNA. The transformants are analyzed to locate the export DNA or a gene comprising it, and the position of the export DNA in the cell's genome is determined; the orientation of the insertion also is determined.