Characterization of the chicken vimentin gene: Single copy gene producing multiple mRNAs

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Abstract
Genomic clones and c[complementary]DNA plasmids were isolated for the intermediate filament protein vimentin from chicken. The identity of the various clones was determined both by mRNA selection and nucleotide sequence analysis. Restriction analysis, hybridization data and heteroduplex studies confirmed that all of the genomic isolates contained overlapping fragments of an identical vimentin gene. No evidence for the existence of a 2nd vimentin gene could be found by a Southern analysis either by using coding fragments from the purified vimentin gene or by using cDNA plasmids as probe. Copy-number experiments verified that the vimentin gene was present only once in the haploid chicken genome. In a RNA blot analysis, at least 2 equally abundant vimentin mRNA species of .apprx. 2200 and 2500 nucleotides in length were detected in all RNA tested. Sequence analysis revealed that the vimentin gene contained 2 sets of tandem polyadenylylation sites, 249 and 532 nucleotides downstream from the stop codon for protein synthesis. The larger mRNA species arise becasue of complete transcription of the 3''-end of the vimentin gene (560 nucleotides of 3'' nontranslated sequence), whereas the smaller mRNA species terminate after the 1st set of polyadenylylation sites.