Phosphorylation of the Spi-B transcription factor reduces its intrinsic stability.
The Spi-B transcription factor is an Ets protein expressed in B lymphoid cells and closely related to the Spi-1/PU.1 oncoprotein. By mutational analysis, we showed that Spi-B is phosphorylated by casein kinase II in vitro on four serine residues. Mutation of these four serines to alanines prevented the phosphorylation of Spi-B in vivo, increased the ability of Spi-B to transactivate expression of a reporter gene and led to a decrease of Spi-B stability. We propose that the phosphorylation of Spi-B may participate in the modulation of Spi-B functional activity by controlling its intracellular protein level.
Ray-Gallet
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D
INSERM, Unité 248, Institut Curie, 26 rue díUlm, 75248, Paris, France.
Moreau-Gachelin
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F
D047390:Casein Kinase II; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D014157:Transcription Factors; C076877:SPIB protein, human; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases