Nuclear matrins: identification of the major nuclear matrix proteins.
A preparative two-dimensional polyacrylamide gel system was used to separate and purify the major Coomassie blue-stained proteins from the isolated rat liver nuclear matrix. Approximately 12 major proteins were consistently found. Of these, 5 proteins represented identified proteins, including nuclear lamins A, B, and C, the nucleolar protein B-23, and residual components of core heterogeneous nuclear ribonucleoproteins. The remaining eight major proteins termed the nuclear matrins consisted of matrin 3 (125 kDa, slightly acidic), matrin 4 (105 kDa, basic), matrins D-G (60-75 kDa, basic), and matrins 12 and 13 (42-48 kDa, acidic). Peptide mapping and two-dimensional immunoblot studies indicate that matrins D-G compose two pairs of related proteins (matrins D/E and F/G) and that none of the matrins resemble the nuclear lamins or any of the other major proteins detected on our two-dimensional gels. Subfractionation immunoblot experiments demonstrated the nearly exclusive localization of matrins F/G and other matrins to the nuclear matrix fraction of the cell. These results were further supported by indirect immunofluorescence microscopy that showed a strictly interior nuclear localization of the matrins in intact cells in contrast to the peripherally located nuclear lamins. We conclude that the nuclear matrins are a major class of proteins of the nuclear matrix interior and are distinct from the nuclear lamins.
Nakayasu
H
H
Department of Biological Sciences, State University of New York, Buffalo 14260.
Berezney
R
R
D000818:Animals; D000906:Antibodies; D034961:Antigens, Nuclear; D015153:Blotting, Western; D002467:Cell Nucleus / Q000737:chemistry* / Q000648:ultrastructure; D015180:Electrophoresis, Gel, Two-Dimensional; D005455:Fluorescent Antibody Technique; D008099:Liver / Q000737:chemistry* / Q000648:ultrastructure; D008970:Molecular Weight; D015530:Nuclear Matrix / Q000737:chemistry / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000032:analysis* / Q000302:isolation & purification; D010449:Peptide Mapping; D051381:Rats
D000906:Antibodies; D034961:Antigens, Nuclear; D009687:Nuclear Proteins