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. 1997 Nov 11;94(23):12473–12478. doi: 10.1073/pnas.94.23.12473

Figure 3.

Figure 3

Cells that perform the logical And operation on input proteins. (A) Expression of the LexOp-lacZ reporter in cells containing TetR-Cdc25 (907–1,589) or GAP as measured by the intensity of blue color on X-Gal medium and by β-galactosidase activity in Miller units. (B) Inferred protein relationships in these cells. In the cell expressing TetR-Cdc25, Cdc25 loads LexA-Ras with GTP, increasing the amount of Ras that is in the GTP bound conformation (black outline) with which B42-c-Raf1 can interact to stimulate transcription of the lacZ reporter, and decreasing the amount of Ras in the GDP-bound conformation (grey outline) with which B42-c-Raf-1 cannot interact. In the cell expressing TetR-GAP, this switch is reversed. In this cell, TetR-GAP stimulates Ras GTPase activity, increasing the amount of Ras in the GDP-bound form (black outline), with which B42-c-Raf1 cannot interact, and decreasing the amount of Ras in the GTP-bound form (grey outline), thus resulting in lowered lacZ output. (C) Table depicting results of these operations on protein inputs. In the table, the 1’s in the first column indicate the presence of B42-Raf, the 0 and 1 in the second column denote, respectively, the presence of TetR-Gap and TetR-Cdc25, and the 0 and 1 in the third column denote respectively low and high outputs of β-galactosidase.