HNRNP PROTEINS AND B23 ARE THE MAJOR PROTEINS OF THE INTERNAL NUCLEARMATRIX OF HELA S3 CELLS

The nuclear matrix is the structure that persists after removal of chr omatin and loosely bound components from the nucleus. It consists of a peripheral lamina-pore complex and an intricate internal fibrogranula r structure. Little is known about the molecular structure of this pro teinaceous internal network. Our aim is to identify the major proteins of the internal nuclear matrix of HeLa S3 cells. To this end, a cell fraction containing the internal fibrogranular structure was compared with one from which this structure had been selectively dissociated. P rotein compositions were quantitatively analyzed after high-resolution two-dimensional gel electrophoresis. We have identified the 21 most a bundant polypeptides that are present exclusively in the internal nucl ear matrix. Sixteen of these proteins are heterogeneous nuclear ribonu cleoprotein (hnRNP) proteins. B23 (numatrin) is another abundant prote in of the internal nuclear matrix. Our results show that most of the q uantitatively major polypeptides of the internal nuclear matrix are pr oteins involved in RNA metabolism, including packaging and transport o f RNA. (C) 1996 Wiley-Liss, Inc.