Contains a 5' end fragment of the Mhc gene, from 450bp upstream of the transcription initiation site, including exon 1, intron 1 and 293bp of exon 2, fused in frame to a 3' end fragment of the Mhc gene, which includes exons 17, 18 and 19, their intervening sequences, and approximately 700bp of 3' flanking sequences.