CHARACTERIZATION OF SOME NUCLEAR MATRIX PROTEINS IN MAIZE

We have prepared a nuclear matrix fraction from maize seedlings and studied its protein composition. Proteins were characterized by immunoblotting analysis, two-dimensional gel fractionation and two-dimensional peptide mapping. Most of them were found to belong to the group of IF-lamina proteins, as has been shown for the matrix proteins from animals. One of these proteins was further classified as the maize version of lamin C since it possessed an isoelectric point in the range characteristic for lamin C from animals, cross-reacted with anti-lamin c antiserum and its two-dimensional peptide map contained most of the spots characteristic of the map of mouse Earlich ascite tumor lamin C. Unlike animal lamins (proteins of molecular masses in the range of 60-75 kDa), the maize lamin C possessed a molecular weight of 42 kDa. A group of proteins possessed molecular masses in the 65- to 75-kDa range and isoelectric points similar to that of animal lamin B. In addition, their 2D peptide maps revealed considerable similarity with the map of lamin B from avian erythrocytes. However, these proteins do not resemble lamin B from EAT cells neither immunologically nor by tryptic peptide mapping. Two proteins of our preparation are not lamin-like. The tryptic peptide maps of the proteins reveal similarity with some animal proteins that bind DNA tightly.