A nuclear matrix association sequence consists of the nucleolar localization signal and the conserved C-terminus. a) Hela cells were transfected with the indicated, myc-tagged constructs and the nuclear matrix was prepared. NM, nuclear matrix preparation; WC, whole cell. Subsequently the cells were stained with an antibody against the myc tag, mounted in DAPI and photographed on a confocal microscope. b) HEK293T cells were transfected with the indicated constructs, fractionated into subcellular fractions, and immunoblotted with the antibodies as indicated. S2, S3 and P3 correspond to the cytoplasmic soluble, nuclear soluble and nuclear insoluble (chromatin and nuclear matrix) fractions, respectively. The data from three independent experiments are illustrated as histograms in which the bars represent the range of band intensities measured with a densitometer. c) HEK293T cells were transfected with myc-tagged SAP30 and SAP30L proteins, and nucleosomes were isolated. In the left upper panel, a Coomassie-stained gel shows release of histones, and an agarose gel (left lower panel) shows the accompanying release of nucleosomal DNA from the nucleus after treatment with micrococcal nuclease. The proteins from each step of nucleosome isolation were analysed on the immunoblot shown in the right panel. The data from the three independent experiments are illustrated in the histograms, as in (b). d) A Kyte-Doolittle Hydrophilicity plot of the nuclear matrix association sequences from proteins of the SAP30 and AML  families. e) A schematic representation of the domains identified in SAP30L. NLS, nuclear localization signal; NoLS, nucleolar localization signal; Protein bd, the protein-binding domain and nuclear matrix association sequence identified in this study. The numbers indicate amino acid positions. The color gradients depict more strongly interacting regions in darker colors. The zinc finger is necessary for proper presentation of these regions to DNA or phosphoinositides.