| pubmed-article:2145793 | pubmed:abstractText | A series of cDNA fragments encoding immunodetectable portions of the human slow/beta, neonatal, and embryonic isoforms of myosin heavy chain (MHC) were isolated from a human fetal muscle cDNA expression library. A 6 kb fragment isolated on a secondary screen represents the first cloned cDNA encoding a full-length vertebrate MHC (the human embryonic isoform). In the 3'-untranslated regions, 70-80% nucleotide sequence homology exists among orthologous human and rat cDNAs, whereas the homology is less than 65% among the paralogous cDNAs. Furthermore, approximately the same level of untranslated sequence conservation is observed at the 5'-terminus of the embryonic transcript. These results suggest that for both the 3'- and the 5'-untranslated domains, the rate of evolutionary sequence divergence is limited by functional constraints. | lld:pubmed |
