EXPRESSION PATTERN AND PARTIAL SEQUENCE-ANALYSIS OF A FETAL BOVINE MYOSIN HEAVY-CHAIN GENE

A fragment of a bovine myosin heavy-chain (MHC) gene approximately 15 kbp in size (designated MHC 67) was isolated from a bovine genomic DNA library. The direction of transcription was determined, and prelimina ry experiments indicated that the gene was expressed in fetal skeletal muscle. The expression pattern of this gene was, therefore, evaluated in detail using northern blots containing RNA from eleven different b ovine muscle and nonmuscle tissues at three developmental ages. A rest riction fragment of clone MHC 67 containing the 3' untranslated sequen ce (which is specific for each MHC gene) was used as a probe. This gen e fragment hybridized predominantly to RNA from fetal skeletal muscles and did not hybridize to RNA from either neonatal or adult skeletal m uscles (red or white), smooth muscle tissue, or nonmuscle tissue. A 7- kb EcoRI fragment containing both translated and untranslated regions surrounding the 3' end of the gene was subcloned into pBluescript II K S+ and partially sequenced. When these bovine sequences were aligned t o that of the human and rat skeletal and cardiac MHC genes, we found t hat these sequences corresponded to exons 31, 32, and 33, and that the y had homology with human perinatal and fetal MHC as high as 90% at th e nucleotide level and 97% at the amino acid level. Comparison of the nucleotide sequences of isoform-specific 3' nontranslated regions from bovine, human, and rat genes further verify that the MHC 67 clone enc odes the bovine fetal or perinatal MHC isoform.