BIOL 200 Lecture Notes - Lecture 27: Allosteric Regulation, Hemoglobin, Protein Kinase A
7 Jun 2016
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Document Summary
Binding of one ligand influences binding of another ligand in a different region of the protein. Ligand binding always influences protein conformation to a certain extent. Positive: change in conformation spreads throughout the protein. Negative: change in conformation spreads throughout the protein. The importin b binding domain (ibb) of importin a bind to the acidic groove. Rangtp binding induces a change in conformation (torsion) that is incompatible with ibb binding. Binding of the 1st a induces changes in conformation that influence binding of b, but alters the conformation of the second subunit, favouring binding of the 2nd a. Cooperativity makes the system more sensitive to small changes in concentration. Kd values in 10-9m to 10-6 m range. Once one is bound, subsequent binding is easier, slope steepens. Binding approaches all or nothing over a much more narrow range of concentration of the ligand.
