Reassembling proteins and chaperones in human nuclear matrix protein fractions

To detect putative filament forming components, nuclear matrix proteins wer e searched for proteins extensively reassembling from urea solution. Eight proteins, ubiquitously occurring in various human cell types, but not appar ent in the cytosol, were registered by means of two-dimensional gel electro phoresis. They consisted of a protein exhibiting a novel amino acid sequenc e; of nuclear lamin B2, RbAp48, and RbAp48; and of four as yet unknown prot eins. Furthermore, partial sequencing, mass spectrometry, and immunodetecti on of proteins demonstrated the presence of molecular chaperones and protei n folding catalysts in the nuclear matrix fractions. In addition to a TCP-1 -related protein, certain members of the heat shock, PDI, and cal reticulin family of proteins were detected. On the basis of the absence of several o ther heat shock proteins in the nuclear matrix fraction, a general contamin ation by cytoplasmic chaperones appears unlikely. J. Cell. Biochem. 74:145- 151, 1999. (C) 1999 Wiley-Liss, Inc.