Identification of transcripts produced from the MCMV IE-3 gene. a) 5'RACE was performed on RNA isolated from MCMV infected M2-10B4 cells at either one or five days p.i. using two nested primer sets. Primer set 1 is located just upstream of the IE-3 stop codon and primer set 2 is located near the beginning of exon 5. Cells were infected at an m.o.i. of either 2 or 0.2. IE-3 FL: full length IE-3 transcript, Ex 2 tc: transcript initiated from the beginning of exon 2, Ex 5-164 tc: transcript initiated from nucleotide 164 within exon 5 (nucleotide 764 of IE-3) and synthesized from primers set 2, Ex 5-1277: transcript initiated from nucleotide 1277 within exon 5 (nucleotide 1879 of IE-3) and synthesized from primer set 1. Numbers underneath each exon show the nucleotide coordinates for the exon. b) Summary of IE-3 transcripts detected and their nucleotide location within the full length IE-3 cDNA.