Distal polar effect

Baugh, L., Le Trong, I., Cerutti, D. S., Gulich, S., Stayton, P. S., Stenkamp, R. E., and Lybrand, T. P. (2010). A distal point mutation in the streptavidin/biotin complex preserves structure but diminishes binding affinity Experimental evidence of electronic polarization effects Biochemistry 49, pp. 4568-4570. 

Thus araB28 is a nonsense mutation at the operator distal end of the araB gene and is still hyperinducible, whereas araBM, a nonsense mutation that maps in the middle of gene araB, produces a strong polar effect (Fig. 4 and Table I). When the effect of nonsense mutations is tested in merodiploids of the type A B jA B (nonsense), the iso-... 

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