Schematic representation of C. elegans cyclin A and cyclin A pseudogenes. The intron/exon structure of cyclin A (cosmid ZK507) is shown with the cyclin box shaded. Below this are shown the six different cyclin A pseudogene structures: regions with homology to exons are represented by boxes and regions homologous to introns by lines (with deletions also marked). The cosmid clones containing each of the genes are shown on the right with the genes actually represented on the schematic in bold. Note that cosmids B0019 and W02A11 overlap and represent only one pseudogene. For each schematic, potential open reading frames (ORFs) are represented by a bar. Black bars represent ORFs with high identity to cyclin A1 (> 70%) and gray bars represent ORFs with no significant identity to cyclin A1. ORFs were predicted by assuming that each pseudogene was fully transcribed and spliced in a manner analogous to the cyclin A gene. The largest ORF was identified in the pseudogene on clone C02B8 and would result in a 75- or 113-amino-acid protein depending on whether the first initiation codon within the pseudogene was used (asterisk) or an initiation codon just 5' of the pseudogene. Frameshifts and point mutations limit the extent of the identity and frequently result in termination codons.