Molecular cloning and sequencing of a murine pgk-1 pseudogene family

Seven genomic mouse DNA fragments carrying pgk-1-homologous regions have been cloned and sequenced. They have to be classified as processed genes because intervening sequences, present in their productive counterpart, are absent. Four pseudogenes (I-IV) represent nearly the complete sequence of pgk-1 cDNA. Two of these genes (I and II), although rather different from the published mouse pgk-1 cDNA in the 3'-untranslated region, represent the actual mouse pgk-1 cDNA sequence in the coding part except for substitutions in the third position of three codons. These genes can code for a functional PGK protein but, lacking as they do classical promoter structures, are probably not expressed. They show the typical characteristics of retroposons, being flanked by A-rich regions and direct repeats which are localized at the positions where the homology with the mouse pgk-1 cDNA is interrupted. Pseudogenes III and IV have numerous mutations. Gene III is also flanked by direct repeats, whereas gene IV is flanked by inverted repeats. The other three genes are flanked by direct repeats localized further inside the target sites. They are truncated and mutated extensively as usually observed with pseudogenes.