Molecular cloning of matrin F/G: A DNA binding protein of the nuclear matrix that contains putative zinc finger motifs.

Abstract

We have isolated a 2.7-kilobase rat liver cDNA clone that contains the entire 544-amino acid coding sequence for matrin F/G. This protein has previously been localized to the internal, fibrogranular areas of the nuclear matrix and shown to bind to DNA on nitrocellulose blots. The predicted amino acid sequence from the coding region of this cDNA shows that this protein contains -50% hydrophobic amino acids with secondary structure predictions suggesting a large percentage of fl-sheet regions. No significant homologies were found with any other known proteins, including the nuclear lamins. The predicted amino acid sequence was also searched for DNA binding motifs. Two putative zinc finger motifs were found. In addition, a 7-mer palindromic sequence (Ser-Ser-Thr-Asn-Thr-Ser-Ser) was discovered within one of these zinc finger DNA binding regions. A possible regulatory role for this element is discussed.The nuclear matrix consists of a nuclear lamina, residual nucleoli, and an internal nuclear matrix (1). It is typically prepared by nuclease, salt, and detergent treatments of isolated nuclei (for review, see ref.2). Many molecular processes have been found associated with the nuclear matrix (2), including DNA replication (3), transcription (4), RNA splicing (5), and attachment of supercoiled DNA loops (6).The nuclear lamins are the most characterized of the nuclear matrix proteins. Analysis of cloned sequences of lamins A and C (7, 8) and lamin B (9) reveal structural similarity to the intermediate filament proteins. In contrast, our knowledge of the rest of the nuclear matrix proteins is very limited. Appropriate two-dimensional analysis has revealed over 200 proteins in the nuclear matrix including those that are common in a variety of cell lines and those that are both cell type and differentiation state dependent (10-12).Research in our laboratory is concentrating on the analysis ofa limited number of major Coomassie blue-stained proteins that are common to nuclear matrices isolated from a variety of mammalian cells. Polyclonal antibodies generated to many of these proteins all show staining of the fibrogranular matrix by immunofluorescence microscopy (13). We have, therefore, termed these proteins the nuclear matrins to distinguish them from the nuclear lamins, which compose the nuclear lamina structure along the periphery ofthe nuclear matrix (H. Nakayasu and R.B., unpublished data).Several of these major nuclear matrix proteins specifically bound DNA on Southwestern blots (40). As a step toward further characterization of the nuclear matrins and their putative role as DNA binding proteins, we have been screening Agtll cDNA expression libraries with our polyclonal antibodies to these matrin proteins. In this manuscript, we report the isolation and sequencing of a cDNA clone for matrin protein F/G4. The predicted amino acid sequence shows a strikingly high content of hydrophobic amino acids (R50o) and predicted /3-sheet secondary structure (-45%) and contains two putative Cys-Cys zinc finger DNA bindi...

Human Prostaglandin Transporter Gene ( hPGT ) is Regulated by Fluid Mechanical Stimuli in Cultured Endothelial Cells and Expressed in Vascular Endothelium in Vivo

“…Sequence analysis of a corresponding cDNA derived from a HUVEC library initially revealed a novel gene that was homologous to a gene encoding the rat matrin F/G. 12,13 Subsequently, Kanai and colleagues 7 reported a longer reading frame within the rat matrin F/G cDNA and demonstrated that this longer form of the protein encoded a member of the family of 12-membrane-spanning transporters that was capable of specifically transporting prostaglandins. This group then identified the human homolog of this molecule and named it hPGT (for human prostaglandin transporter).…”

Fibroblast Growth Factor Receptor-1 (FGFR1) Nuclear Dynamics Reveal a Novel Mechanism in Transcription Control

“…The resulting NM was washed with the extraction buffer. Isolation of the NM was verified by the removal of DNA (DAPI staining) and retention of matrin-3 protein, known to be concentrated in the NM (Hakes and Berezney, 1991).…”

Chicken MAR-Binding Protein ARBP Is Homologous to Rat Methyl-CpG-Binding Protein MeCP2

“…Most likely, this association is mediated by defined proteins that specifically bind to MAR/SARs. A number of proteins that fulfill this definition have been identified, characterized, and cloned (2,9,10,15,25,28,46,47,52). While some MAR-binding proteins seem to have additional roles in RNA processing and transport, others function mainly as structuring proteins at the level of higher-order chromatin organization.…”