Nuclear matrix binding proteins

Raziuddin A, Court D, Sarkar FH, Liu YL, Kung H, Raziuddin R (1997) A c-erbB-2 promoter-specific nuclear matrix protein from human breast tumor tissues mediates NF-kappaB DNA binding activity. / Biol Chem 272(25) 15715-15720... 

Heparin has been found to bind a large number of proteins (Table 3). The biological activity of heparin and related polysaccharides is usually ascribed to their interaction with heparin-binding proteins. These proteins can be classified into classes including (1) enzymes, (2) protease inhibitors, (3) lipoproteins, (4) growth factors, (5) chemokines, (6) selectins, (7) extracellular matrix proteins, (8) receptor proteins, (9) viral coat proteins, (10) nuclear proteins, and (11) other proteins (1). Many heparin-binding proteins are enzymes and enzyme inhibitors. For example, proteases in the coagulation cascade, such as factors Ha, IXa, Xa, Xlla, and Villa, are heparin-... 

It is apparent from the above discussion that Ki-67 is present in the nucleus of proliferating cells and is an indicator of the growth fraction in tumor cells. It is primarily a DNA-binding protein that plays a crucial role in the maintenance or regulation of cell division. This protein may also function as a matrix for chromosomal DNA or contribute to the condensation of the chromosomes or be involved in breakdown of the nuclear membrane before mitosis (Duchrow et al., 1994). The association of Ki-67 with RNA in the nucleoli and with the DNA with nuclear matrix suggests that the antigen plays a role in transcriptional processes as a structural protein by mediating between nuclear DNA and nucleolar RNA. 

Steroid receptors control gene expression in target cells. An understanding of the molecular interactions between receptors and specific nuclear components is crucial for elucidating the mechanism of hormone action. Receptor binding to at least three structural elements of nuclei has been described. These include the nuclear matrix, nucleoacidic chromatin proteins (acceptor proteins), and specific DNA sequences in 5 upstream elements of hormone responsive genes. 

Hakes, D.J. and Berezney, R. (1991) Molecular cloning of matrin F/G a DNA binding protein of the nuclear matrix that contains putative zinc finger motifs. Proceedings of the National Academy of Sciences ofthe, United States of America,, 6186-6190. 

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