Sequencing of full-length and low-molecular-weight isoforms of CD3δ and CD3γ shows alternative exon splicing. Amplified transcripts were sequenced by dideoxy chain termination and separated on a 5% polyacrylamide gel. Sequences corresponding to the full-length CD3δ and CD3γ transcripts (A and C) were compared with the sequences from the low-molecular-weight isoforms (B and D). Arrows point to the splice junctions for each sequence. The sequences show alternatively spliced isoforms that lack exon 3 from the CD3δ molecule and exons 3 through 5 from the CD3γ molecule.