EXPRESSION OF CDNA CLONES BY COUPLED IN-VITRO TRANSCRIPTION TRANSLATION AND TRANSFECTION INTO COS-1 CELLS - PROTEIN MAPPING IN 2-DIMENSIONAL GELS

We present two procedures that can be used to map proteins in two-dime nsional gels if the cDNA is at hand. The first procedure, which is ill ustrated with the expression of cDNAs encoding the fatty acid binding protein 5 (FABP 5), psoriasin and stratifin; makes use of the in vitro transcription/translation assay marketed by Promega. The procedure is simple and allows the mapping of the primary translation product in a very short time. The second method - which faithfully reproduces post -translational modifications - is based on the expression of cDNAs tra nsfected into COS-1 cells using a eukaryotic expression plasmid. This procedure is illustrated with the expression of cDNAs encoding Ha-ras p21 and rab 11, two small GTP-binding proteins known to undergo comple x modifications.