IDENTIFICATION OF HUMAN COMMON NUCLEAR-MATRIX PROTEINS AS HETEROGENEOUS NUCLEAR RIBONUCLEOPROTEIN-H AND RIBONUCLEOPROTEIN-H' BY SEQUENCING AND MASS-SPECTROMETRY

Nuclear-matrix proteins were prepared from different rat and human cel ls and separated by two-dimensional gel electrophoresis. By computer-a ssisted analysis of the images, two of the proteins were identified as ubiquitously occurring (common) nuclear-matrix proteins, which appear ed in tissue-dependent concentrations. The two proteins that originate d from human blood mononuclear cells were analyzed further. Tryptic di gests of the blotted proteins were analyzed by partial peptide sequenc ing and matrix-assisted laser-desorption ionization-time-of-flight mas s spectrometry. The two human common nuclear-matrix proteins were iden tified as heterogeneous nuclear ribonucleoproteins (hnRNP) H and H' or their variants. Furthermore, mass analysis revealed details on the N terminus of hnRNP H.