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Site-directed mutagenesis of the cGMP phosphodiesterase γ subunit from bovine rod outer segments: Role of separate amino acid residues in the interaction with catalytic subunits and transducin α subunit

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Abstract

The recombinant and 21 mutant phosphodiesterase (PDE) γ subunit (PDEγ) genes were expressed by sequential transcription and translation in vitro. Inhibitory properties of these mutants and their interactions with PDE catalytic and transducin α subunits were studied. The interaction of the PDE γ subunit with the catalytic ones proceeds in two steps — primary binding and inhibition. The central region of the PDEγ molecule enriched with the basic amino acid residues (particularly, Lys-29, Lys-31 and Arg-33), is involved in the primary binding, and the PDEγ C-terminus plays the key role in inhibition. The spatial orientation of the C-terminus is of great importance here. The PDEγ C-terminus also affects binding to catalytic moieties.

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    1

    Present address: Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehorst 76100, Israel.

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