Structural Features of the Noncatalytic cGMP Binding Sites of Frog Photoreceptor Phosphodiesterase Using cGMP Analogs
نویسندگان
چکیده
منابع مشابه
Structural features of the noncatalytic cGMP binding sites of frog photoreceptor phosphodiesterase using cGMP analogs.
The cGMP-specific phosphodiesterase (PDE) of retinal photoreceptors is a central regulatory enzyme in the visual transduction pathway of vertebrate vision. Although the mechanism of activation of PDE by transducin is well understood, the role of the noncatalytic cGMP binding sites located on the catalytic subunits of PDE remains obscure. We report here for the first time the molecular basis of ...
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The binding of cGMP to the noncatalytic sites on two isoforms of the phosphodiesterase (PDE) from mammalian rod outer segments has been characterized to evaluate their role in regulating PDE during phototransduction. Nonactivated, membrane-associated PDE (PDE-M, alpha beta gamma2) has one exchangeable site for cGMP binding; endogenous cGMP remains nonexchangeable at the second site. Non-activat...
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The rod photoreceptor phosphodiesterase (PDE) is unique among all known vertebrate PDE families for several reasons. It is a catalytic heterodimer (alphabeta); it is directly activated by a G-protein, transducin; and its active sites are regulated by inhibitory gamma subunits. Rod PDE binds cGMP at two noncatalytic sites on the alphabeta dimer, but their function is unclear. We show that transd...
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The photoreceptor 3':5'-cyclic nucleotide phosphodiesterase (PDE) is the central enzyme of visual excitation in rod photoreceptors. The hydrolytic activity of PDE is precisely regulated by its inhibitory gamma subunit (Pgamma), which binds directly to the catalytic site. We examined the inhibition of frog rod outer segment PDE by endogenous Pgamma, as well as by synthetic peptides corresponding...
متن کاملcGMP binding sites on photoreceptor phosphodiesterase: role in feedback regulation of visual transduction.
A central step in vertebrate visual transduction is the rapid drop in cGMP levels that causes cGMP-gated ion channels in the photoreceptor cell membrane to close. It has long been a puzzle that the cGMP phosphodiesterase (PDE) whose activation causes this decrease contains not only catalytic sites for cGMP hydrolysis but also noncatalytic cGMP binding sites. Recent work has shown that occupancy...
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ژورنال
عنوان ژورنال: Journal of Biological Chemistry
سال: 1998
ISSN: 0021-9258
DOI: 10.1074/jbc.273.10.5557