Schematic map of intron-tagged c-Myc epitope vectors. The positions of restriction endonuclease cleavage sites are shown in parentheses. Functional elements of the plant gene expression cassette are highlighted by arrowheaded and striped boxes. The lower section shows polylinker sequences flanking the c-Myc epitope coding region which is interrupted by intron IV2 of the potato ST-LS1 gene. A BamHI site in pGIGI facilitates subcloning of cDNA sequences from the yeast two-hybrid vector pACT2 in-frame with the c-Myc epitope coding sequence. Polylinker sequences flanking the coding region of the c-Myc epitope in pLOLA and pGIGI are identical to those which flank the intron-tagged HA epitopes in the previously described vectors pPILY and pMENCHU (22), respectively. Amp, ampicillin resistance gene; f1 Ori and OriC, f1 phage and ColE1 plasmid replication origins, respectively; 35S, duplicated enhancer regions in the promoter of cauliflower mosaic virus 35S RNA gene (CaMV35S).