Reciprocal effects of an inhibitory factor on catalytic activity and noncatalytic cGMP binding sites of rod phosphodiesterase

Journal Article · Tue Jun 01 04:00:00 EDT 1982 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.79.12.3702· OSTI ID:6219398

Yamazaki, A; Bartucca, F; Ting, A; Bitensky, M W

In illuminated rod outer segment membranes, GTP and guanosine 5'-(..beta.., ..gamma..-imido)triphosphate (p(NH)ppG) have reciprocal effects on cGMP phosphodiesterase (PDEase; 3':5'-cyclic-nucleotide 5'-nucleotidohydrolase, EC 3.1.4.17) activity and cGMP binding to noncatalytic sites on that enzyme. Two micromolar p(NH)ppG increased PDEase activity more than 2-fold while inhibiting cGMP binding more than 40%. Reduction of noncatalytic cGMP binding, which followed addition of p(NH)ppG, was not a result of PDEase activation. Both effects of p(NH)ppG were completely dependent on the presence of bleached rhodopsin. A heat-stable factor has been found to inhibit PDEase activity and also to stimulate cGMP binding to noncatalytic cGMP binding sites. Addition of p(NH)ppG reversed the effects of this factor on both PDEase activity and cGMP binding. During purification of this material, the activity peaks for both PDEase inhibition and activation of noncatalytic cGMP binding comigrated on both Blue Sepharose CL-6B column chromatography and sucrose density gradients centrifugation, suggesting that the same factor could be responsible for both inhibition of PDEase activity and enhancement of noncatalytic cGMP binding. Limited tryptic proteolysis of PDEase, which markedly reduced cGMP binding to the noncatalytic sites, and experiments using highly purified cAMP (free of cGMP) as substrate for PDEase showed that the binding of cGMP to noncatalytic sites was not required for the heat-stable inhibitory factor to inhibit PDEase activity. We discuss possible relationships between the regulation of PDEase and the binding of cGMP to noncatalytic sites.

• Research Organization: Los Alamos National Lab., NM
• OSTI ID: 6219398
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 79; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMP
BODY
BODY AREAS
CHEMICAL BONDS
CHEMICAL REACTIONS
DATA
ENZYME ACTIVITY
ENZYME INHIBITORS
ENZYMES
ESTERASES
EXPERIMENTAL DATA
EYES
FACE
GUANYLIC ACID
HEAD
HYDROLASES
INFORMATION
NUCLEOTIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHODIESTERASES
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
PIGMENTS
RECEPTORS
SENSE ORGANS
TEMPERATURE DEPENDENCE
VISION