While characterizing the
hsp70 gene family from Caenorhabditis elegans we encountered an unusual member of this family. Sequence data reveal that the
hsp-2ps gene is a pseudogene of the constitutively expressed, heat-inducible
hsp-1 gene. Two stop codons generated near the 5' end of the sequence as well as several frameshift mutations and a large internal deletion confirm the identification of
hsp-2ps as a pseudogene. The nucleotide substitution rate of the third codon position was twice that of the first and second codon positions, suggesting that the
hsp-2ps gene was nonfunctional since the time of the duplication event. The
hsp-2ps gene duplicates a region of the
hsp-1 gene that lies exclusively within the transcribed region and retains the introns. We feel that the
hsp-2ps gene was produced by a transpositional duplication event, which occurred approximately 8.5 million years ago.