BACKGROUND: Scaffold attachment factor A (SAF-A) participates in the regulation 
of gene expression by organizing chromatin into transcriptionally active domains 
and by interacting directly with RNA polymerase II.
METHODOLOGY: Here we use co-localization, co-immunoprecipitation (co-IP) and in 
situ proximity ligation assay (PLA) to identify Brahma Related Gene 1 (BRG1), 
the ATP-driven motor of the human SWI-SNF chromatin remodeling complex, as 
another SAF-A interaction partner in mouse embryonic stem (mES) cells. We also 
employ RNA interference to investigate functional aspects of the SAF-A/BRG1 
interaction.
PRINCIPAL FINDINGS: We find that endogenous SAF-A protein interacts with 
endogenous BRG1 protein in mES cells, and that the interaction does not solely 
depend on the presence of mRNA. Moreover the interaction remains intact when 
cells are induced to differentiate. Functional analyses reveal that dual 
depletion of SAF-A and BRG1 abolishes global transcription by RNA polymerase II, 
while the nucleolar RNA polymerase I transcription machinery remains unaffected.
CONCLUSIONS: We demonstrate that SAF-A interacts with BRG1 and that both 
components are required for RNA Polymerase II Mediated Transcription.