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Allelic inactivation

Mutually exclusive regulation

The immune system uses DNA recombination to activate one particular gene by bringing promoter and enhancer regions into close proximity [1].

To explain the mutually exclusive expression, gene conversion is another possible mechanism. In yeast mating-type switches [2] or in Trypanosoma antigenicity changes [3] the chosen copy from a group of related genes is transferred to an expression cassette located at a distant site.

The mutually exclusive regulation of olfactory receptors remains to be determined [4].

[1] Tonegawa, S. (1983) Nature 302, 575-581.
[2] Strathern, J. N. et al. (1982) Cell 31, 183-192.
[3] Borst, P. (1991) Immunol. Today 12, 29-33.
[4] Serizawa, S. et al. (2000) Nature Neuroscience, 3, 687-693.