An attempt to discriminate catalytic and regulatory proton binding sites in membrane-bound, thiol-reduced chloroplast ATPase

Biochemistry ◽  
1992 ◽  
Vol 31 (17) ◽  
pp. 4239-4247 ◽  
Author(s):  
Marie Valerio ◽  
Yaroslav De Kouchkovsky ◽  
Francis Haraux
Keyword(s):  
Binding Sites ◽  
Proton Binding ◽  
Membrane Bound

scholarly journals Proton-Binding Motifs of Membrane-Bound Proteins: From Bacteriorhodopsin to Spike Protein S

2021 ◽  
Vol 9 ◽  
Author(s):  
Ana-Nicoleta Bondar
Keyword(s):  
Hydrogen Bond ◽  
Binding Sites ◽  
Coupled Model ◽  
Protein S ◽  
Specific Protein ◽  
Spike Protein ◽  
Sequence Motifs ◽  
Proton Binding ◽  
Hydrogen Bond Networks ◽  
Membrane Bound

Membrane-bound proteins that change protonation during function use specific protein groups to bind and transfer protons. Knowledge of the identity of the proton-binding groups is of paramount importance to decipher the reaction mechanism of the protein, and protonation states of prominent are studied extensively using experimental and computational approaches. Analyses of model transporters and receptors from different organisms, and with widely different biological functions, indicate common structure-sequence motifs at internal proton-binding sites. Proton-binding dynamic hydrogen-bond networks that are exposed to the bulk might provide alternative proton-binding sites and proton-binding pathways. In this perspective article I discuss protonation coupling and proton binding at internal and external carboxylate sites of proteins that use proton transfer for function. An inter-helical carboxylate-hydroxyl hydrogen-bond motif is present at functionally important sites of membrane proteins from archaea to the brain. External carboxylate-containing H-bond clusters are observed at putative proton-binding sites of protonation-coupled model proteins, raising the question of similar functionality in spike protein S.

scholarly journals Further studies on the topography of the N-terminal region of human platelet glycoprotein IIIa. Localization of monoclonal antibody epitopes and the putative fibrinogen-binding sites

1991 ◽  
Vol 274 (2) ◽  
pp. 457-463 ◽  
Author(s):  
J J Calvete ◽  
J Arias ◽  
M V Alvarez ◽  
M M Lopez ◽  
A Henschen ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Binding Sites ◽  
Human Platelet ◽  
Binding Domain ◽  
Terminal Region ◽  
Platelet Glycoprotein ◽  
Gamma Chain ◽  
Fibrinogen Binding ◽  
Glycoprotein Iiia ◽  
Membrane Bound

The precise localization of the epitopes for six monoclonal antibodies specific for the N-terminal region of human platelet glycoprotein IIIa (GPIIIa) was determined. The epitope for P37, a monoclonal antibody that inhibits platelet aggregation, was found at GPIIIa 101-109, flanked by the epitopes for P23-3 (GPIIIa 16-28), P23-4 (GPIIIa 83-91), P23-5 (GPIIIa 67-73), P23-7 (GPIIIa 114-122) and P40 (GPIIIa 262-302), and very close to the early chymotryptic cleavage site of GPIIIa in whole platelets (Phe-100). When the amino acid sequence of GPIIIa was searched for peptide sequences hydropathically complementary to the fibrinogen gamma-chain C-terminal (gamma 400-411) and A alpha-chain RGD-containing peptides, none was found for the gamma 400-411, two (GPIIIa 128-132 and 380-384) were found complementary to fibrinogen A alpha 571-575 and two (GPIIIa 109-113 and 129-133) were found for A alpha 94-99. Two of these putative fibrinogen-binding sites overlap with each other, and a third one overlaps with the epitope for P37. These findings reinforce the earlier suggestion that the N-terminal region of GPIIIa is involved in fibrinogen binding, and suggest the existence in GPIIIa of either multiple or alternative RGD-binding sites or one RGD-binding domain with several moieties. Finally, early chymotryptic cleavage of GPIIIa in whole platelets liberates to the soluble fraction the peptide stretch Ser-101-Tyr-348, which carries the epitope for P37 and the putative binding sites for fibrinogen. The rest of the molecule, together with the GPIIb-resistant moiety, remains membrane-bound. This leads us to propose that the fibrinogen-binding domain of GPIIIa is not involved in the binding to GPIIb to form the Ca2(+)-dependent GPIIb-GPIIIa complex.

Localization and analysis of natriuretic peptide receptors in the gills of the toadfish, Opsanus beta (teleostei)

1994 ◽  
Vol 267 (6) ◽  
pp. R1437-R1444 ◽  
Author(s):  
J. A. Donald ◽  
T. Toop ◽  
D. H. Evans
Keyword(s):  
Natriuretic Peptide ◽  
Binding Sites ◽  
Peptide Receptors ◽  
Natriuretic Peptide Receptors ◽  
Major Band ◽  
Opsanus Beta ◽  
Secondary Lamellae ◽  
Membrane Bound ◽  
Type C ◽  
Specific Ligand

The distribution and nature of natriuretic peptide binding sites was determined in the gills of the toadfish, Opsanus beta. Specific 125I-labeled rat atrial natriuretic peptide (rANP) and 125I-labeled porcine C-type natriuretic peptide (pCNP) binding sites were observed on the afferent and efferent filamental arteries and lamellar arterioles, and on the marginal channels of the secondary lamellae. In both section autoradiography and competition assays, the binding of both ligands was completely displaced by 1 microM rANP and 1 microM pCNP, but residual binding was observed with 1 microM of the type C natriuretic peptide receptor (NPR-C)-specific ligand C-ANF. Electrophoresis of gill membranes cross-linked with 125I-rANP showed a major band at 75 kDa and a fainter band at 140 kDa. Both rANP and pCNP significantly stimulated the production of cGMP above basal levels; C-ANF had no stimulatory effect. These data show that the intrafilamental gill vasculature of toadfish contains a major population of natriuretic peptide receptors very similar to mammalian clearance receptors and a smaller population of receptors that are linked to a membrane-bound guanylate cyclase.

Regulation of the F1-ATPase from mitochondria of Vigna sinensis (L.) Savi cv. Pitiuba by spermine, spermidine, putrescine, Mg2+, Na+, and K+

1981 ◽  
Vol 59 (1) ◽  
pp. 60-66 ◽  
Author(s):  
Horst W. Peter ◽  
Moema Rodrigues Pinheiro ◽  
Maria Silva Lima
Keyword(s):  
Binding Sites ◽  
Vigna Sinensis ◽  
F1 Atpase ◽  
Membrane Bound

Mitochondria from Vigna sinensis (L.) Savi cv. Pitiuba contain the polyamines spermine, spermidine, and putrescine. The membrane-bound F1-ATPase from mitochondria of Vigna sinensis is activated by these polyamines at physiological concentrations. The effect of polyamines on the membrane-bound F1-ATPase is dependent on the concentrations of Na+, K+, MgATP, and Mg2+. Excess Na+ or K+ prevents the activation of the membrane-bound F1-ATPase by spermine and spermidine, but not by putrescine. The most pronounced effects were observed at low MgATP concentrations in the absence of Na+ and K+. At [MgATP] = 0.08 mM, spermine activation of the membrane-bound F1-ATPase was 130%.The membrane-bound F1-ATPase is slightly activated by Mg2+ at lower concentrations and strongly inhibited by Mg2+ at higher concentrations. Activation as well as inhibition is dependent on the substrate MgATP concentration. Although there is competition between Mg2+ and MgATP, the binding sites for these two ligands are different (pseudocompetitive inhibition). The inhibition of the membrane-bound F1-ATPase can be reversed by polyamines. There is evidence that the binding sites for Mg2+ and polyamines are identical.The F1-ATPase detached from the membrane is neither activated by polyamines nor inhibited by Mg2+. Therefore, the binding sites for Mg2+ and polyamines seem to be localized on the membrane.

scholarly journals Independent Contribution of Extracellular Proton Binding Sites to ASIC1a Activation

2013 ◽  
Vol 288 (48) ◽  
pp. 34375-34383 ◽  
Author(s):  
Aram J. Krauson ◽  
Anna C. Rued ◽  
Marcelo D. Carattino
Keyword(s):  
Binding Sites ◽  
Proton Binding ◽  
Independent Contribution

scholarly journals The Autocrine Mitogenic Loop of the Ciliate Euplotes raikovi: The Pheromone Membrane-bound Forms Are the Cell Binding Sites and Potential Signaling Receptors of Soluble Pheromones

2000 ◽  
Vol 11 (4) ◽  
pp. 1445-1455 ◽  
Author(s):  
Claudio Ortenzi ◽  
Claudio Alimenti ◽  
Adriana Vallesi ◽  
Barbara Di Pretoro ◽  
Antonietta La Terza ◽  
...  
Keyword(s):  
Recombinant Proteins ◽  
Binding Sites ◽  
Homologous Proteins ◽  
Guanine Nucleotide Binding Protein ◽  
Genes Encoding ◽  
Membrane Bound ◽  
Guanine Nucleotide Binding ◽  
Signaling Receptors ◽  
Euplotes Raikovi ◽  
Mitotic Proliferation

Homologous proteins, denoted pheromones, promote cell mitotic proliferation and mating pair formation in the ciliate Euplotes raikovi, according to whether they bind to cells in an autocrine- or paracrine-like manner. The primary transcripts of the genes encoding these proteins undergo alternate splicing, which generates at least two distinct mRNAs. One is specific for the soluble pheromone, the other for a pheromone isoform that remains anchored to the cell surface as a type II protein, whose extracellular C-terminal region is structurally equivalent to the secreted form. The 15-kDa membrane-bound isoform of pheromone Er-1, denoted Er-1mem and synthesized by the same E. raikovi cells that secrete Er-1, has been purified from cell membranes by affinity chromatography prepared with matrix-bound Er-1, and its extracellular and cytoplasmic regions have been expressed as recombinant proteins. Using the purified material and these recombinant proteins, it has been shown that Er-1mem has the property of binding pheromones competitively through its extracellular pheromone-like domain and associating reversibly and specifically with a guanine nucleotide-binding protein through its intracellular domain. It has been concluded that the membrane-bound pheromone isoforms of E. raikovi represent the cell effective pheromone binding sites and are functionally equipped for transducing the signal generated by this binding.

scholarly journals Isolation of a Single Carboxyl-Carboxylate Proton Binding Site in the Pore of a Cyclic Nucleotide–Gated Channel

1999 ◽  
Vol 114 (1) ◽  
pp. 71-84 ◽  
Author(s):  
James A. Morrill ◽  
Roderick MacKinnon
Keyword(s):  
Binding Site ◽  
Cyclic Nucleotide ◽  
Binding Sites ◽  
Wild Type ◽  
Protonation Site ◽  
Proton Binding ◽  
Cng Channel ◽  
Ph Dependent ◽  
Conductance States ◽  
Single Channel Currents

The pore of the catfish olfactory cyclic nucleotide–gated (CNG) channel contains four conserved glutamate residues, one from each subunit, that form a high-affinity binding site for extracellular divalent cations. Previous work showed that these residues form two independent and equivalent high-pKa (∼7.6) proton binding sites, giving rise to three pH-dependent conductance states, and it was suggested that the sites were formed by pairing of the glutamates into two independent carboxyl-carboxylates. To test further this physical picture, wild-type CNG subunits were coexpressed in Xenopus oocytes with subunits lacking the critical glutamate residue, and single channel currents through hybrid CNG channels containing one to three wild-type (WT) subunits were recorded. One of these hybrid channels had two pH-dependent conductance states whose occupancy was controlled by a single high-pKa protonation site. Expression of dimers of concatenated CNG channel subunits confirmed that this hybrid contained two WT and two mutant subunits, supporting the idea that a single protonation site is made from two glutamates (dimer expression also implied the subunit makeup of the other hybrid channels). Thus, the proton binding sites in the WT channel occur as a result of the pairing of two glutamate residues. This conclusion places these residues in close proximity to one another in the pore and implies that at any instant in time detailed fourfold symmetry is disrupted.

scholarly journals THE MEMBRANE ATTACK MECHANISM OF COMPLEMENT

1973 ◽  
Vol 138 (2) ◽  
pp. 438-451 ◽  
Author(s):  
William P. Kolb ◽  
Hans J. Müller-Eberhard
Keyword(s):  
Cell Surface ◽  
Target Cell ◽  
Complement Activation ◽  
Binding Sites ◽  
Sedimentation Coefficient ◽  
Cytolytic Activity ◽  
Stable Complex ◽  
Free Solution ◽  
Alternate Pathway ◽  
Membrane Bound

The membrane attack mechanism of complement, C5 to C9, has previously been postulated to associate on the target cell surface to a stable decamolecular complex with a calculated mol wt of 995,000. A soluble and stable complex consisting of C5, C6, C7, C8, and C9 has now been demonstrated to arise as a consequence of complement activation by the classical or alternate pathway. It has a sedimentation coefficient of 22.5S and a mol wt of 1 million daltons, and it migrates on electrophoresis at pH 8.6 as an α-globulin. The stable and soluble C5b-9 complex cannot bind to erythrocytes and has no demonstrable cytolytic activity. However, due to partially unsaturated binding sites for C9, it can bind additional C9 and thus function as an inhibitor of lysis of EAC1-8 by C9. These results support the concept according to which the membrane-bound attack system of complement represents a stable, decamolecular assembly of C5b-9. Unlike its analogue in free solution, the membrane-bound complex is cytolytically active.

Sign in / Sign up

Export Citation Format

Share Document