Both a ubiquitous factor mTEF-1 and a distinct muscle-specific factor bind to the M-CAT motif of the myosin heavy chain beta gene.
The A element, a fourteen base pair sequence in the rabbit myosin heavy chain (HC) beta promoter (-276/-263), contains the M-CAT motif, a cis-acting element found in several muscle-specific genes. The A element is essential for muscle-specific transcription of the myosin HC beta gene. Recently, we have identified both muscle-specific and ubiquitous factors (A1 and A2 factors, respectively) that bind to the A element. Since the sequence of the A element is very similar to the GTIIC motif in the SV40 enhancer, we examined the relationship between A-element-binding factors and a GTIIC binding factor TEF-1, recently isolated from HeLa cells. The GTIIC motif was bound by the A1 and A2 factors in muscle nuclear extracts and competed with the A element for DNA-protein complex formation. Antibody against human TEF-1 'supershifted' the ubiquitous A2 factor-DNA complex, but did not alter the mobility of the muscle-specific A1 factor-DNA complex. We isolated a murine cDNA clone (mTEF-1) from a cardiac cDNA library. The clone is highly homologous to Hela cell TEF-1. The in vitro transcription/translation product of mTEF-1 cDNA bound to the A element, and the DNA binding property of mTEF-1 was identical to that of the A2 factor. Transfection of mTEF-1 cDNA into muscle and non-muscle cells confirmed that mTEF-1 corresponds to A2, but not to A1 factors. The mTEF-1 mRNA is expressed abundantly in skeletal and cardiac muscles, kidney and lung, but it is also expressed at lower levels in other tissues. These results suggest that the M-CAT binding factors consist of two different factors; the ubiquitous A2 is encoded by mTEF-1, but the muscle-specific A1 factor is distinct from mTEF-1.
Department of Medicine, Harvard Medical School, Boston, MA 02215.
N
N
Shimizu
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G
Smith
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S
Izumo
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009218:Myosins / Q000235:genetics*; D009687:Nuclear Proteins; D009928:Organ Specificity; D011401:Promoter Regions, Genetic; D013539:Simian virus 40 / Q000235:genetics; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D009124:Muscle Proteins; D009687:Nuclear Proteins; D000091262:TEA Domain Transcription Factors; C057182:TEAD1 protein, human; C083215:Tead1 protein, mouse; D014157:Transcription Factors; D004247:DNA; D009218:Myosins