21,000 LB19 B-lymphoblastoid cell line: 160,000 MCF-7 breast carcinoma cell line Molecules/cell
||Human Homo sapiens
||Mark D. Biggin, Animal Transcription Networks as Highly Connected, Quantitative Continua, Developmental cell Volume 21, Issue 4, 18 October 2011, Pages 611-626 DOI 10.1016/j.devcel.2011.09.008 p.617 table 1 Table - link PubMed ID22014521
||Ma L, Wagner J, Rice JJ, Hu W, Levine AJ, Stolovitzky GA. A plausible model for the digital response of p53 to DNA damage. Proc Natl Acad Sci U S A. 2005 Oct 4 102(40):14266-71.PubMed ID16186499
||Primary source abstract: "Recent observations show that the single-cell response of p53 to ionizing radiation (IR) is "digital" in that it is the number of oscillations rather than the amplitude of p53 that shows dependence on the radiation dose. [Investigators] present a model of this phenomenon. In [their] model, double-strand break (DSB) sites induced by IR interact with a limiting pool of DNA repair proteins, forming DSB-protein complexes at DNA damage foci. The persisting complexes are sensed by ataxia telangiectasia mutated (ATM), a protein kinase that activates p53 once it is phosphorylated by DNA damage."
||P.617 left column bottom paragraph: "A survey of all credible published estimates that [investigator] could find for four well studied species suggests that most animal transcription factors are expressed at 10,000–300,000 molecules per nucleus (Table 1). These estimates are further supported by [his] own experience and that of many other biochemists who have purified additional endogenous transcription factors with similar yields to the proteins in Table 1. It has long been recognized that such high cellular concentrations are sufficient to thermodynamically drive each transcription factor molecule to reside on DNA most of the time (Lin and Riggs, 1975, von Hippel et al., 1974, Yamamoto and Alberts, 1976)." See BNID 100420