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Skeletal muscle actin mRNA. Characterization of the 3' untranslated region
Abstract:
Plasmids p749, p106, and p150 contain cDNA inserts complementary to rat skeletal muscle actin mRNA. Nucleotide sequence analysis indicates the following sequence relationships: p749 specifies codons 171 to 360; p150 specifies codons 357 to 374 together with 120 nucleotides of the 3'-non-translated region; p106 specifies the last actin amino acid codon, the termination codon and the entire 3' non-translated region. Plasmid p749 hybridized with RNA extracted from rat skeletal muscle, cardiac muscle, smooth (stomach) muscle, and from brain. It also hybridizes well with RNA extracted from skeletal muscle and brain of dog and chick. Plasmid p106 hybridized specifically with rat striated muscles (skeletal and cardiac muscle) mRNA but not with mRNA from rat stomach and from rat brain. It also hybridized to RNA extracted from skeletal muscle of rabbit and dog but not from chick. Thermal stability of the hybrids and sensitivity to S1 digestion also indicated substantial divergence between the 3' untranslated end of rat and dog skeletal muscle actins. The investigation shows that the coding regions of actin genes are highly conserved, whereas the 3' non-coding regions diverged considerably during evolution. Probes constructed from the 3' non-coding regions of actin mRNAs can be used to identify the various actin mRNA and actin genes.
Insights
Actin gene coding regions are highly conserved across species, but their 3' non-coding regions show significant evolutionary divergence. These non-coding regions can identify different actin messenger RNAs (mRNAs) and genes.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Genetics
Background:
- Actin is a crucial protein involved in muscle contraction and cellular structure.
- Understanding actin gene evolution requires analyzing both coding and non-coding regions.
Purpose of the Study:
- To investigate the conservation and divergence of actin gene sequences, focusing on coding and 3' non-translated regions.
- To assess the utility of 3' non-coding regions as probes for identifying specific actin mRNAs and genes.
Main Methods:
- Nucleotide sequence analysis of plasmids containing rat skeletal muscle actin cDNA inserts (p749, p106, p150).
- Hybridization experiments using these plasmids with RNA from various rat tissues and other species (dog, chick, rabbit).
- Analysis of hybrid thermal stability and S1 nuclease digestion to assess sequence similarity.
Main Results:
- Plasmid p749 (coding region) showed broad hybridization across different rat tissues and species.
- Plasmid p106 (3' non-coding region) demonstrated species- and tissue-specific hybridization, particularly with striated muscle mRNA.
- Significant divergence was observed in the 3' untranslated regions between rat and dog skeletal muscle actins.
Conclusions:
- Actin gene coding sequences are highly conserved during evolution.
- The 3' non-coding regions of actin genes have diverged considerably, offering specificity for identifying different actin variants.
- Probes derived from 3' non-coding regions are valuable tools for distinguishing actin mRNAs and genes.