Bacterial clones containing inserted DNA sequences specific for α-tubulin, β-tubulin, β-actin and γ-actin have been constructed from mRNA of embryonic chick brain. Plasmids containing approximately 75, 90 and >90%, respectively, of the sequences present in α-tubulin, β-tubulin and β-actin mRNAs have been isolated as well as clones containing parts of the extensive 3′ untranslated regions of the β- and γ-actin mRNAs. The sequences for the two tubulins do not cross hybridize. Hybridization of labeled, cloned probes for each of the tubulins with chicken DNA digested with several restriction endonucleases reveals about four fragments for α- and four for β-tubulin. This seems to be the number of genes, since both the 5′ and 3′ ends of either cloned tubulin cDNAs hybridize to at least four common fragments in genomic DNA which has been digested with restriction endonucleases. The tubulin probes are able to hybridize under stringent conditions to DNA of all vertebrate genomes tested, as well as to sea urchin DNA, but not to yeast DNA. In digested sea urchin sperm DNA there are more than 20 different fragments which hybridize to both the 5′ and 3′ ends of the tubulin cDNAs. A full-length β-actin cDNA clone hybridizes to 4-7 bands in restricted chicken DNA and cross hybridizes to DNA from every other species tested, including sea urchin and yeast. Hybridization to chicken DNA of cloned probes specific for the 3′ untranslated regions of β- and γ-actin mRNA indicates that the β sequence is present only once in the genome and the γ is present in at most three copies. Neither 3′ untranslated sequence is conserved evolutionarily.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)