A tobacco bZip transcription activator (TAF-1) binds to a G-box-like motif conserved in plant genes

EMBO J. 1991 Jul;10(7):1793-802.


Tobacco nuclear extract contains a factor that binds specifically to the motif I sequence (5'-GTACGTGGCG-3') conserved among rice rab genes and cotton lea genes. We isolated from a tobacco cDNA expression library, a partial cDNA clone encoding a truncated derivative of a protein designated as TAF-1. The truncated TAF-1 (Mr = 26,000) contains an acidic region at its N-terminus and a bZip motif at its C-terminus. Using a panel of motif I mutants as probes, we showed that the truncated TAF-1 and the tobacco nuclear factor for motif I have similar, it not identical, binding specificities. In particular, both show high-affinity binding to the perfect palindrome 5'-GCCACGTGGC-3' which is also known as the G-box motif. TAF-1 mRNA is highly expressed in root, but the level is at least 10 times lower in stem and leaf. Consistent with this observation, we found that a motif I tetramer, when fused to the -90 derivative of the CaMV 35S promoter, is inactive in leaf of transgenic tobacco. The activity, however, can be elevated by transient expression of the truncated TAF-1. We conclude from these results that TAF-1 can bind to the G-box and related motifs and that it functions as a transcription activator.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • CCAAT-Enhancer-Binding Proteins*
  • Cloning, Molecular
  • DNA-Binding Proteins / genetics*
  • Gene Expression
  • Glucuronidase / biosynthesis
  • Glucuronidase / genetics*
  • Leucine Zippers / genetics*
  • NFI Transcription Factors
  • Nuclear Proteins / genetics*
  • Plant Proteins / genetics*
  • Plants, Toxic*
  • Protein Binding
  • RNA, Messenger / metabolism
  • Sequence Homology, Nucleic Acid
  • Tobacco / genetics*
  • Trans-Activators / genetics*
  • Trans-Activators / isolation & purification
  • Trans-Activators / metabolism
  • Transcription Factors*
  • Y-Box-Binding Protein 1


  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • NFI Transcription Factors
  • Nuclear Proteins
  • Plant Proteins
  • RNA, Messenger
  • Trans-Activators
  • Transcription Factors
  • Y-Box-Binding Protein 1
  • YBX1 protein, human
  • Glucuronidase

Associated data

  • GENBANK/M55400
  • GENBANK/M55401
  • GENBANK/M55402
  • GENBANK/M65224
  • GENBANK/S60919
  • GENBANK/S60920
  • GENBANK/X58576
  • GENBANK/X58577
  • GENBANK/X59082
  • GENBANK/X60363