Nonhistone Chromosomal Proteins in Synchronized HeLa Cells

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 69; no. 11; pp. 3345 - 3349
• Main Authors: Bhorjee, Jaswant S., Pederson, Thoru
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.11.1972; National Acad Sciences
• Subjects: Biological Sciences: Biochemistry; Carbon Isotopes; Cell cycle; Cell Division; Cell Fractionation; Chromatin; Chromatin - analysis; Chromatin - isolation & purification; DNA; DNA, Neoplasm - analysis; DNA, Neoplasm - biosynthesis; Electrophoresis; Electrophoresis, Disc; Electrophoresis, Polyacrylamide Gel; Gels; HeLa cells; HeLa Cells - analysis; HeLa Cells - cytology; HeLa Cells - metabolism; Histones; Histones - analysis; Interphase; Kinetics; Leucine - metabolism; Mitosis; Molecular Weight; Nonhistone chromosomal proteins; Nucleoproteins - analysis; Sodium Dodecyl Sulfate; Thymidine - metabolism; Tritium
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.69.11.3345

Chromatin was isolated from synchronized HeLa cells at different stages of the cell division cycle and fractionated into DNA, histones, and nonhistone proteins. Electrophoresis of the nonhistone proteins in sodium dodecyl sulfate-polyacrylamide gels revealed a highly reproducible pattern of 22 bands, having estimated molecular weights of 15,000-180,000, with 85% (by mass) over 40,000. The amounts of some nonhistone proteins varied during the cell cycle by as much as 50%, while others remained at a constant level. One group of nonhistone proteins (molecular weight 75,000) was greatly reduced just before the start of DNA replication (S-phase), then returned to normal levels in the mid-S phase. These results are discussed with regard to the possible role of nonhistone proteins in regulating chromosome structure and function.