Determination of heterogeneous transcription start points of two c-myc genes from the common carp (Cyprinus carpio)

We determined the heterogeneous transcription start points (tsp) Of two c-myc genes from the common carp (Cyprinus carpio), tetraploid teleost, by the oligo-capping method and showed the existence of the first exon. This is the first report on the existence of the first exons of the fish c-myc gene. Transcription of the two carp c-myc genes started from at least four sites in CAM1, locating from -752 to -381 bp upstream of the translation start site, and from 12 sites in CAM2, locating from -586 to -413 bp upstream respectively. The first introns of CAM1 and CAM2 were deduced to be 335 and 356 bp, respectively. They shared 86.9% nt identity, lower than those of the second exons (94.1%), and third exons (92.3%), which suggest that the first exons evolved faster. No nt identities were found between the c-myc first exons of carp and other vertebrates. The putative promotor regions in CAM1 and CAM;! contained no obvious TATA or CCAAT boxes in the expected positions. (C) 2000 Published by Elsevier Science B.V. All rights reserved.