Non-histone chromatin proteins of B lymphocytes stimulated by lipopolysaccharide.
The synthesis of non-histone chromatin proteins and nucleoplasmic proteins has been followed during lipopolysaccharide-induced division and differentiation of murine B lymphocytes. Synthesis was measured by pulse labelling with [3H]leucine, extraction of proteins was under conditions designed to prevent proteolysis and analysis of labelled proteins was by polyacrylamide gel electrophoresis. The average specific activity of non-histone chromatin proteins increased 3-fold, to a maximum, after culture for 24 h with lipopolysaccharide. Comparison of the relative synthesis of individual proteins (stimulation index) reveals three distinct responses: (1) those in the largest group show low stimulation indices, generally less than two; (2) a group of four proteins have indices between 4 and 5; (3) two proteins (molecular weights 21 000 and 22 000) both show an index of 5 at 24 h rising to between 7 and 8 by 48 h when the average specific activity is falling, coinciding with the period of rapid differentiation to high rate IgM secretion. Additionaly at this time, a newly labelled protein (Mr = 36 500) appears in the nucleoplasm followed by a second protein (Mr = 63 000) appearing between 48 and 72 h. The patterns of change are consistent with an overall increase in non-histone chromatin proteins synthesis, necessary for cell division, with superimposed specific changes in synthesis of non-histone chromatin proteins which could be related to regulation of cell differentiation.
D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000096:biosynthesis*; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010447:Peptide Hydrolases / Q000378:metabolism; D012486:Salmonella typhimurium
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D008070:Lipopolysaccharides; D010447:Peptide Hydrolases; D007930:Leucine