1A4X:
reference: Adaptation of an enzyme to regulatory function: structure of Bacillus subtilis PyrR, a pyr RNA-binding attenuation protein and uracil phosphoribosyltransferase., Tomchick DR, Turner RJ, Switzer RL, Smith JL, Structure 1998 Mar 15;6(3):337-50. PMID: 9551555

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