BIOL 3409 Study Guide - Midterm Guide: Lung Cancer, P16, Exponential Growth
24 Apr 2018
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P53 is a transcription factor => binds specific dna sequences: must be in nucleus to work if it is trapped in cytoplasm it cannot stimulate transcription. These results indicated that the wild-type allele of p53 really functions to suppress cell proliferation, and that p53 acquires growth-promoting powers when it sustains a point mutation in its reading frame. Because of this discovery, the p53 gene was eventually categorized as a tumor suppressor gene. Deletion of both p53 gene copies from the mouse germ line had no significant effect on the development of the great majority of p53 / embryos. Therefore, p53 could not be considered to be a simple negative regulator of cell proliferation during normal development. Mutant versions of p53 interfere with normal p53 function. In the knudson scheme, an evolving pre-malignant cell can only reap substantial benefit once it has lost both functional copies of a tumor suppressor gene that has been holding back its proliferation.
