Nuclear matrix. Isolation and characterization of a framework structure from rat liver nuclei

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• The nucleus contains a structural framework known as the nuclear matrix.
• This matrix is a significant component of isolated nuclei, primarily proteinaceous with minor nucleic acids, carbohydrates, and phospholipids.

Purpose of the Study:

• To isolate and characterize the nuclear matrix.
• To identify the protein composition and structural localization of the nuclear matrix.

Main Methods:

• Isolation and characterization of the nuclear matrix.
• Sequential treatment with DNase and RNase to obtain the nuclear protein matrix.
• Electron microscopy for structural analysis.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein identification.

Main Results:

• The nuclear protein matrix consists of residual nucleolar structures, an internal framework, and a nuclear envelope layer with pore complexes.
• SDS-PAGE revealed three major polypeptides (P-1, P-2, P-3) and minor fractions in the nuclear matrix.
• These major polypeptides are also present in nuclear envelopes and nucleoli, but not in chromatin.
• Cytochrome oxidase activity was detected, indicating association with nuclear membrane proteins.

Conclusions:

• The nuclear matrix is a distinct structural framework within the nucleus.
• Its major protein components are localized to specific nuclear regions: envelope, nucleoli, and interchromatinic structures.
• The nuclear matrix is associated with nuclear membrane proteins.