Figure 3.

Protein composition of the high-salt and amine-modified nuclear matrices. CaSki cell proteins were labeled with [³⁵S]methionine, extracted with 0.5% Triton X-100, and the chromatin digested with HaeIII/PstI. Chromatin was subsequently removed either by sequential 0.25 M ammonium sulfate/2 M NaCl extraction or by sulfo-NHS treatment. The proteins remaining with the nuclear matrix were analyzed by SDS/PAGE and fluorography. The protein composition of the amine-modified nuclear matrix (lane 1) was similar, but not identical, to the protein complement of the high-salt nuclear matrix (lane 2). There was also a greater total retention of proteins in the amine-modified nuclear matrix.