MAJOR INTERNAL NUCLEAR MATRIX PROTEINS ARE COMMON TO DIFFERENT HUMAN CELL-TYPES

The nuclear matrix may be involved in the structural and functional or ganization of the cell nucleus. However, we still do not understand th e molecular basis of the intranuclear fibrogranular network that is pa rt of the nuclear matrix. We recently described a method to identify i nternal nuclear matrix proteins [Mattern et al. (1996): J Cell Biochem 62:275-289], which was done by comparing two nuclear matrix preparati ons: one with and one without the internal structure by using quantita tive two-dimensional gel electrophoresis. In the present study, we use the same approach to compare the nuclear matrix proteins of four diff erent human cell types to investigate whether they have a similar inte rnal nuclear matrix protein composition. Major nuclear matrix proteins present in all these cell types likely represent the base of the inte rnal nuclear matrix. We demonstrate that the 25 most abundant internal nuclear matrix proteins are common to all four cell types. Together, these common proteins represent more than 75% of the total internal nu clear matrix protein mass in each cell type. This set of proteins incl udes B23 and most hnRNP proteins. The quantity of most of these protei ns is very similar in the four cell types. The fact that the internal nuclear matrix consists mainly of hnRNP proteins, which may be involve d in transcription, transport, and processing of hnRNA, supports the i dea that the internal nuclear matrix is the result of these processes. (C) 1997 Wiley-Liss, Inc.