Unusual sequence conservation in the 5' and 3' untranslated regions of the sea urchin spec mRNAs

The Spec1 and Spec2 mRNAs (Strongylocentrotus purpuratus ectoderm mRNAs) represent a small gene family that encodes 10-12 members of the troponin C superfamily of calcium-binding proteins. These mRNAs and proteins accumulate in the aboral (dorsal) ectoderm of sea urchin embryos and larvae. Using gen...

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Bibliographic Details
Published in:Journal of molecular evolution 1987, Vol.25 (2), p.126-133
Main Authors: HARDIN, P. E, KLEIN, W. H
Format: Article
Language:English
Subjects:
Animals
Base Sequence
Biological and medical sciences
Cloning, Molecular
DNA - metabolism
Fundamental and applied biological sciences. Psychology
Genes
Genes. Genome
Molecular and cellular biology
Molecular genetics
Molecular Sequence Data
Nucleic Acid Hybridization
Protein Biosynthesis
RNA, Messenger - genetics
Sea Urchins - genetics
Strongylocentrotus purpuratus
Troponin - genetics
Troponin C
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Summary:The Spec1 and Spec2 mRNAs (Strongylocentrotus purpuratus ectoderm mRNAs) represent a small gene family that encodes 10-12 members of the troponin C superfamily of calcium-binding proteins. These mRNAs and proteins accumulate in the aboral (dorsal) ectoderm of sea urchin embryos and larvae. Using genomic and cDNA clones, we have compared the sequences of four Spec mRNAs: Spec1, Spec2a, Spec2c, and Spec2d. The mRNAs all have at least 120 bases of 5' untranslated leader, approximately 450 bases of open reading frame, and 900 bases (Spec1) or 1250 bases (Spec2a, 2c, 2d) of 3' untranslated trailer. Unexpectedly, when long stretches of 5' untranslated regions or 3' untranslated regions are compared to one another, they are found to be less divergent than the protein-coding regions. Comparing Spec2d, the most divergent member of the family, with the other Spec mRNAs shows that while the protein-coding regions are 60-62% matched, the untranslated regions are greater than 80% matched. Comparisons among Spec1, Spec2a, and Spec2c demonstrate similar but less dramatic conservation of untranslated regions. Our data imply that the Spec gene family has evolved differently from most gene families, with mutations accumulating most rapidly in intron regions, less rapidly in protein-coding regions, and least rapidly in 5' and 3' untranslated regions.
ISSN:0022-2844
1432-1432
DOI:10.1007/BF02101754