Identification of a new cAMP response element-binding factor by southwestern blotting.
We have identified in mammalian cells a novel cyclic AMP response element (CRE)-binding protein of molecular mass 47 kDa. This protein was not recognized by either the CREB-327/341 or c-Jun antisera, and its tissue distribution did not overlap with those of the CREB and Jun families. For example, hepatoma and placental tissue did not contain the 47-kDa DNA-binding protein, but did contain the CREB isoforms. On the other hand, S49 lymphoma cells contained a high level of the 47-kDa DNA-binding protein but did not contain a 47-kDa Jun-related protein which was found in normal liver and hepatoma. This new 47-kDa factor bound to the CRE in the dephosphorylated form, and phosphorylation of the protein by the catalytic subunit of protein kinase A completely abolished its DNA-binding activity. The isoforms of the CREB-327/341 family, on the other hand, bound to DNA in the phosphorylated form, and alkaline phosphatase treatment reduced significantly their interaction with CRE sequence. This reverse effect of phosphorylation/dephosphorylation on the DNA-binding property of this new 47-kDa protein in particular distinguishes it from other known CREB factors and suggests that the protein might play a unique role in the regulation of cAMP-mediated transcription.
Kwast-Welfeld
J
J
Institute for Biological Sciences, National Research Council, Ottawa, Canada.
de Belle
I
I
Walker
P R
PR
Whitfield
J F
JF
Sikorska
M
M
D000818:Animals; D001483:Base Sequence; D017362:Cyclic AMP Response Element-Binding Protein / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D007106:Immune Sera; D015151:Immunoblotting / Q000379:methods; D008099:Liver / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D008223:Lymphoma; D008297:Male; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D015345:Oligonucleotide Probes; D010766:Phosphorylation; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D011915:Rats, Inbred BUF; D017207:Rats, Sprague-Dawley; D012045:Regulatory Sequences, Nucleic Acid; D014407:Tumor Cells, Cultured
D017362:Cyclic AMP Response Element-Binding Protein; D007106:Immune Sera; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes