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Building a cellular switch: more lessons from a good egg
Author(s) -
Ferrell James E.
Publication year - 1999
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/(sici)1521-1878(199910)21:10<866::aid-bies9>3.0.co;2-1
Subject(s) - xenopus , oocyte , biology , microbiology and biotechnology , population , lysogenic cycle , signal transduction , somatic cell , bacteriophage , genetics , embryo , escherichia coli , demography , sociology , gene
Xenopus oocytes mature in response to the steroid hormone progesterone. At the level of a population of oocytes, the response is graded—the higher the concentration of progesterone, the larger the fraction of oocytes that will mature—but at the level of the individual oocyte, the response is all‐or‐none. The all‐or‐none character of this cell fate switch is hypothesized to arise out of two properties of the signal transduction machinery that mediates maturation, positive feedback, and ultrasensitivity. This combination of positive feedback plus ultrasensitivity crops up again and again in cellular switches, from the lysis‐lysogeny switch in phage‐infected bacteria to the action potential in neurons. BioEssays 21:866–870, 1999. © 1999 John Wiley & Sons, Inc.