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pubmed:abstractText |
The purpose of this study was to characterize the complete cDNA sequence encoding the rabbit smooth muscle myosin heavy chain (MHC) and determine the exon/intron organization at the 5' end of the corresponding gene. The full-length cDNA sequence of 6644 base pairs encoding a protein of 1972 amino acids was generated from two cDNA clones: PBRUC1 (approximately 6.3 kilobases), isolated from a rabbit uterus cDNA library, and PBRU-PCR33 (420 base pairs), produced by primer extension and PCR amplification. Compared with the chicken smooth muscle MHC sequence [Yanagisawa, M., Hamada, Y., Katsuragawa, Y., Imamura, M., Mikawa, T. & Masaki, T. (1987) J. Mol. Biol. 198, 143-157] the rabbit MHC shares about 90% amino acid identity in the S1 globular head region but shows a striking sequence divergence at the junction between the 25-kDa and 50-kDa proteolytic fragments of the functionally important S1 head domain. Genomic cloning shows that the rabbit smooth muscle MHC gene is large and has an unusual exon/intron organization at the 5' end. The first eight contiguous exons are located within a region of at least 70 kilobases of genomic DNA. Some introns span several kilobases of DNA and others at the 5' end show a high degree of intron conservation in the Mg(2+)-ATPase domain when compared with more distantly related sarcomeric MHC genes. Primer extension and S1 nuclease mapping analysis demonstrate that transcription initiates from a single site in the rabbit smooth muscle MHC gene.
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pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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