Conformation change binding

B) Activation by a conformational change. Binding of the SH2 domains of p85, the regulatory subunit of PI-3 kinase to pTyr sites on activated receptors releases an autoinhibitory constraint that stimulates the catalytic domain (pi 10). PI-3 kinase catalyzes the phosphorylation of the 3 positions of the inositol ring of Ptdlns(4)P and Ptdlns(4,5)P2 to generate Ptdlns(3,4)P2 and Ptdlns(3,4,5)P3, respectively. (After Schlessinger, 2000). 

Van Aalten, D.M.F., Findlay, J.B.C., Amadei, A., Berendsen,H.J.C. Essential dynamics of the cellular retinol-binding protein. Evidence for ligand-induced conformational changes. Protein Engin. 8 (1995) 1129-1136. 

Calcium is the trigger behind the muscle contraction process (24,25). Neural stimulation activates the release of stored Ca(Il) resulting in a dramatic increase in free calcium ion levels. The subsequent binding of Ca(Il) resulting in a dramatic increase in free calcium ion levels. The subsequent binding of Ca(Il) to the muscle protein troponin C provides the impetus for a conformational change in the troponin complex and sets off successive events resulting in muscle contraction. 

Figure 5.27 Schematic representation of a model for the conformational change of hemagglutinin that at low pH brings the fusion peptide to the same end of the molecule as the receptor binding site. The fusion peptide (purple) is at the end of heUx A about 100 A away from the receptor binding site in the high pH form. In the low pH fragment this region of helix A has moved about 100 A towards the area where the receptor binding sites are expected to be in the intact hemagglutinin molecule. (Adapted from D. Stuart, Nature 371 19-20, 1994.)...

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