Binding of rat liver nucleoproteins to the distal regulatory element of the α1-acid glycoprotein gene

Abstract

The binding of insoluble nuclear matrix and soluble nucleoproteinsto DRE, the distal responsive element (-5300/ -5150) that is required for the transcriptional regulation of the rat α1-acid glycoprotein (AGP) gene, was examined in the basal state when AGP transcription was low, and during the acute-phase response when its transcription was increased. By South-Western analysis of nuclear matrix preparations it was established that as a result of the acute-phase response, in addition to binding to a 40 kDa protein (p40), the distal responsive element exhibited a considerably increased binding to p45, and a slightly less prominent but enhanced binding to p29, p35, p37 and p55 proteins in relation to the control. South-Western analysis of the soluble nucleoprotein preparation revealed an increased binding to p35, p37 and p45, and an unchanged binding to p29 and p70. The presence of polypeptides with apparently identical molecular masses in the different nuclear components points to the existence of dynamic interactions between nuclear compartments that are related to the functional properties of the nucleus.