The CArG promoter sequence is necessary for muscle-specific transcription of the cardiac actin gene in Xenopus embryos.
Promoter sequences required for activation of the Xenopus cardiac actin gene in embryonic muscle were analysed by micro-injecting chimeric actin/beta-globin genes into the two-cell Xenopus embryo. Transcription was monitored during subsequent differentiation of embryonic muscle and non-muscle tissues. The effect of a variety of mutations including internal deletions and linker scan mutations between -64 and -396 within the cardiac actin promoter were tested. This region contains four copies of a conserved motif, the CArG box, common to vertebrate striated muscle acting gene promoters. In the Xenopus cardiac actin gene, the most proximal of these motifs (CArG box 1) located at -80, was essential for muscle-specific transcription. Other CArG motifs could functionally substitute for CArG box 1 when placed in this position. CArG boxes 3 and 4 bound the same activity in a neurula embryo nuclear extract as CArG box 1 and the amount of this binding activity was constant through early development.
Mohun
T J
TJ
Cancer Research Campaign, Molecular Embryology Research Group, Cambridge, UK.
Taylor
M V
MV
Garrett
N
N
Gurdon
J B
JB
D000199:Actins / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D014982:Xenopus laevis / Q000196:embryology
D000199:Actins; D004247:DNA