title: Rat metallothionein-1 structural gene and three pseudogenes, one of which contains 5'-regulatory sequences.
abstract: As shown by Southern blot analysis, the metallothionein-1 (MT-1) genes in rats comprise a multigene family. We present the sequence of the MT-1 structural gene and compare its features with other metallothionein genes. Three MT-1 pseudogenes which we sequenced apparently arose by reverse transcription of processed mRNA transcripts. Two of these, MT-1 psi a and MT-1 psi c, are retrogenes which derive from the MT-1 mRNA, having diverged from the MT-1 gene 6.9 and 2.6 million years ago, respectively. The third, MT-1 psi b, differs from the MT-1 cDNA by only three nucleotide alterations. Surprisingly, MT-1 psi b also preserves sequence homology for 142 base pairs 5' to the transcription initiation site of the parent gene; it contains a promoter sequence sufficient for specifying metal ion induction. We identified, by S1 nuclease mapping, an RNA polymerase II initiation site 432 base pairs 5' of the MT-1 transcription initiation site of the MT-1 structural gene which could explain the formation of the mRNA precursor to this pseudogene. We were unable to detect MT-1 psi b transcripts, either in liver tissue or after transfection. We conclude that the absence of detectable transcripts from this pseudogene is due to either a reduced level of transcription or the formation of unstable transcripts as a consequence of the lack of a consensus sequence normally found 3' of transcription termination in the MT-1 structural gene.
mesh_terms: D000123:Acetyltransferases / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase; D004262:DNA Restriction Enzymes; D005796:Genes; D005809:Genes, Regulator; D008114:Liver Neoplasms, Experimental / Q000378:metabolism; D008668:Metallothionein / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D051381:Rats
chemical_list: D008668:Metallothionein; D000123:Acetyltransferases; D015500:Chloramphenicol O-Acetyltransferase; D004262:DNA Restriction Enzymes