| First Author | Georgopoulos K | Year | 1992 |
| Journal | Mol Cell Biol | Volume | 12 |
| Issue | 2 | Pages | 747-57 |
| PubMed ID | 1531087 | Mgi Jnum | J:49688 |
| Mgi Id | MGI:1289991 | Doi | 10.1128/mcb.12.2.747 |
| Citation | Georgopoulos K, et al. (1992) Functionally distinct isoforms of the CRE-BP DNA-binding protein mediate activity of a T-cell-specific enhancer. Mol Cell Biol 12(2):747-57 |
| abstractText | Expression of the CD3 delta gene of the T-cell receptor (TCR) complex is regulated by a T-cell-specific enhancer. A highly conserved 40-bp motif (element delta A) within the CD3 delta enhancer is responsible for mediating its activity and specificity. Element delta A exhibits sequence similarities to the cyclic AMP response element (CRE) but does not respond to changes in the level of cyclic AMP. Using the delta A element as a probe, we have isolated three cDNA clones encoding three distinct protein isoforms, products of differential splicing and alternate promoter usage of the CRE-BP gene. These isoforms share the DNA binding and dimerization domains at the C terminus of the protein but differ at their N termini. In transfection assays, their activities as transcription regulators differ: CRE-BP2 is a potent activator, CRE-BP3 is a weak activator, and CRE-BP1 is transcriptionally inert. Mutations in the basic region of the CRE-BP1 protein which abrogate its ability to bind DNA render this protein a dominant repressor of the delta A enhancer. Antibodies to the CRE-BP protein interact specifically with the ubiquitous and predominantly T-cell-restricted nuclear complexes that bind to the delta A element and suggest the presence of this protein in homo- and heterodimeric complexes. Since the delta A motif is also present in the enhancer and promoter of the TCR alpha and beta genes, the CRE-BP isoforms may mediate expression of other members of the CD3/TCR complex during T-cell development. |
