cGMP is tightly bound to bovine retinal rod phosphodiesterase

Journal Article · Thu Jun 01 04:00:00 EDT 1989 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.86.11.4311· OSTI ID:5443064

Gillespie, P G; Beavo, J A ^[1]

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1. Univ. of Washington, Seattle (USA)

Although the total concentration of cGMP in rod outer segments is thought to be substantially greater than the free concentration, no quantitatively relevant site for the bound cGMP has been described in mammalian photoreceptors. They have found that preparations of purified bovine rod photoreceptor cyclic nucleotide phosphodiesterase (PDE) contain 1.8 {plus minus} 0.3 mol of tightly bound cGMP per mol of PDE. When subunits of the purified PDE were separated by reverse-phase HPLC, a peak of material having spectral properties characteristic of a guanine ring was seen. This material was identified as cGMP. When incubated with 1{mu}M ({sup 3}H)cGMP, only 0.1 mol of ({sup 3}H)cGMP bound per mol of purified PDE. Scatchard plots of ({sup 3}H)cGMP binding have indicated that two classes of binding sites are present on the rod PDE. The observation that stoichiometric amounts of cGMP are tightly bound to PDE accounts for the inability to purify the bovine rod PDE on cGMP affinity columns or to demonstrate stoichiometric high-affinity binding sites with ({sup 3}H)cGMP. More significantly, the tightly bound cGMP may resolve the apparent discrepancy between the free and total cGMP concentrations of photoreceptor outer segments.

• OSTI ID: 5443064
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (USA) Vol. 86:11; ISSN PNASA; ISSN 0027-8424
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
AMINES
AROMATICS
AZAARENES
BIOCHEMICAL REACTION KINETICS
BODY
BODY AREAS
CHEMICAL REACTIONS
CHROMATOGRAPHY
CROSS-LINKING
ENZYMES
ESTERASES
EYES
FACE
GUANINE
GUANOSINE
GUANYLIC ACID
HEAD
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROLASES
HYDROXY COMPOUNDS
KINETICS
LIQUID COLUMN CHROMATOGRAPHY
MEMBRANE PROTEINS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PHOSPHODIESTERASES
POLYMERIZATION
PROTEINS
PURINES
REACTION KINETICS
RECEPTORS
RETINA
RIBOSIDES
SENSE ORGANS
SEPARATION PROCESSES
TRITIUM COMPOUNDS
VENOMS