Specific interaction of TAFII105 with OCA-B is involved in activation of octamer-dependent transcription.
TAF(II)105 is a TFIID-associated factor highly expressed in B lymphocytes. This subunit is found in a small portion of TFIID complexes and is homologous to human TAF(II)130 and Drosophila TAF(II)110. In the present study we show that TAF(II)105 is involved in transcription activation directed by the B cell-specific octamer element found in many B cell-specific genes. B cells overexpressing TAF(II)105 display higher octamer-dependent transcription, whereas expression of a C-terminal truncated form of TAF(II)105 inhibits octamer transcription in a dominant negative manner. In addition, antibodies directed against TAF(II)105 specifically inhibit octamer-dependent transcription. Reporter gene analysis revealed that TAF(II)105 elevates octamer transcription in the presence of OCA-B, a cofactor subunit of Oct1 and Oct2 proteins. In vitro binding assays and functional studies established that the effect of TAF(II)105 on octamer activity involves interaction of TAF(II)105 with octamer-binding complexes via the C-terminal activation domain of OCA-B. These findings link TAF(II)105 coactivator function to B cell-specific transcription.
Wolstein
O
O
Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
Silkov
A
A
Revach
M
M
Dikstein
R
R
D001704:Biopolymers; D002460:Cell Line; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D035381:TATA-Binding Protein Associated Factors; D015534:Trans-Activators / Q000378:metabolism*; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
D001704:Biopolymers; D017931:DNA Primers; D004268:DNA-Binding Proteins; C091546:POU2AF1 protein, human; C101881:TAF4B protein, human; D035381:TATA-Binding Protein Associated Factors; D015534:Trans-Activators; D035362:Transcription Factor TFIID; D014157:Transcription Factors