scholarly journals The versatile molecular complex component LC8 promotes several distinct steps of flagellar assembly

2012 ◽  
Vol 198 (1) ◽  
pp. 115-126 ◽  
Author(s):  
Anjali Gupta ◽  
Dennis R. Diener ◽  
Priyanka Sivadas ◽  
Joel L. Rosenbaum ◽  
Pinfen Yang
Keyword(s):  
Molecular Complex ◽  
Binding Sites ◽  
Molecular Complexes ◽  
Terminal Region ◽  
Radial Spoke ◽  
Complex Component ◽  
Flagellar Assembly ◽  
A Subunit ◽  
Docking Proteins ◽  
Base Formation

LC8 is present in various molecular complexes. However, its role in these complexes remains unclear. We discovered that although LC8 is a subunit of the radial spoke (RS) complex in Chlamydomonas flagella, it was undetectable in the RS precursor that is converted into the mature RS at the tip of elongating axonemes. Interestingly, LC8 dimers bound in tandem to the N-terminal region of a spoke phosphoprotein, RS protein 3 (RSP3), that docks RSs to axonemes. LC8 enhanced the binding of RSP3 N-terminal fragments to purified axonemes. Likewise, the N-terminal fragments extracted from axonemes contained LC8 and putative spoke-docking proteins. Lastly, perturbations of RSP3’s LC8-binding sites resulted in asynchronous flagella with hypophosphorylated RSP3 and defective associations between LC8, RSs, and axonemes. We propose that at the tip of flagella, an array of LC8 dimers binds to RSP3 in RS precursors, triggering phosphorylation, stalk base formation, and axoneme targeting. These multiple effects shed new light on fundamental questions about LC8-containing complexes and axoneme assembly.

scholarly journals Polymer Optical Waveguide Sensor Based on Fe-Amino-Triazole Complex Molecular Switches

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
Muhammad Shaukat Khan ◽  
Hunain Farooq ◽  
Christopher Wittmund ◽  
Stephen Klimke ◽  
Roland Lachmayer ◽  
...  
Keyword(s):  
Molecular Complex ◽  
Electromagnetic Interference ◽  
Optical Power ◽  
Uv Curing ◽  
Molecular Complexes ◽  
Core Material ◽  
Absorption Bands ◽  
Electronic Temperature ◽  
Polymer Waveguide ◽  
Temperature Detection

We report on a polymer-waveguide-based temperature sensing system relying on switchable molecular complexes. The polymer waveguide cladding is fabricated using a maskless lithographic optical system and replicated onto polymer material (i.e., PMMA) using a hot embossing device. An iron-amino-triazole molecular complex material (i.e., [Fe(Htrz)2.85(NH2-trz)0.15](ClO4)2) is used to sense changes in ambient temperature. For this purpose, the core of the waveguide is filled with a mixture of core material (NOA68), and the molecular complex using doctor blading and UV curing is applied for solidification. The absorption spectrum of the molecular complex in the UV/VIS light range features two prominent absorption bands in the low-spin state. As temperature approaches room temperature, a spin-crossover transition occurs, and the molecular complex changes its color (i.e. spectral properties) from violet-pink to white. The measurement of the optical power transmitted through the waveguide as a function of temperature exhibits a memory effect with a hysteresis width of approx. 12 °C and sensitivity of 0.08 mW/°C. This enables optical rather than electronic temperature detection in environments where electromagnetic interference might influence the measurements.

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.

scholarly journals Structure, function, and regulation of myosin 1C.

2005 ◽  
Vol 52 (2) ◽  
pp. 373-380 ◽  
Author(s):  
Barbara Barylko ◽  
Gwanghyun Jung ◽  
Joseph P Albanesi
Keyword(s):  
Plasma Membrane ◽  
Binding Sites ◽  
Subcellular Location ◽  
Lipid Binding ◽  
Tail Domain ◽  
Anionic Lipid ◽  
Myosin I ◽  
Docking Proteins ◽  
Neck Domain ◽  
Anionic Lipids

Myosin 1C, the first mammalian single-headed myosin to be purified, cloned, and sequenced, has been implicated in the translocation of plasma membrane channels and transporters. Like other forms of myosin I (of which eight exist in humans) myosin 1C consists of motor, neck, and tail domains. The neck domain binds calmodulins more tightly in the absence than in the presence of Ca(2+). Release of calmodulins exposes binding sites for anionic lipids, particularly phosphoinositides. The tail domain, which has an isoelectic point of 10.5, interacts with anionic lipid headgroups. When both neck and tail lipid binding sites are engaged, the myosin associates essentially irreversibly with membranes. Despite this tight membrane binding, it is widely believed that myosin 1C docking proteins are necessary for targeting the enzyme to specific subcellular location. The search for these putative myosin 1C receptors is an active area of research.

Distinct functional contributions of 2 GABP–NRF-2 recognition sites within the context of the human TOMM70 promoter

2006 ◽  
Vol 84 (5) ◽  
pp. 813-822 ◽  
Author(s):  
José R. Blesa ◽  
José Hernández-Yago
Keyword(s):  
Chromatin Immunoprecipitation ◽  
Binding Sites ◽  
Site Directed Mutagenesis ◽  
Outer Mitochondrial Membrane ◽  
Mobility Shift ◽  
A Subunit ◽  
Expression Evidence ◽  
Electrophoretic Mobility Shift Assays

TOMM70 is a subunit of the outer mitochondrial membrane translocase that plays a major role as a receptor of hydrophobic preproteins targeted to mitochondria. We have previously reported 2 binding sites for the transcription factor GABP–NRF-2 in the promoter region of the human TOMM70 gene that are important in activating transcription. To assess the functionality and actual role of these sites, chromatin immunoprecipitation, site-directed mutagenesis, and electrophoretic mobility shift assays were carried out. We conclude that GABP–NRF-2 binds in vivo to the TOMM70 promoter, and that the 2 GABP–NRF-2 binding sites of the promoter have different functional contributions in promoting TOMM70 expression. Evidence is provided that they work in an additive manner as single sites.

Studying the Cu binding sites in the PrP N-terminal region: a test case for ab initio simulations

2007 ◽  
Vol 36 (7) ◽  
pp. 841-845 ◽  
Author(s):  
S. Furlan ◽  
G. La Penna ◽  
F. Guerrieri ◽  
S. Morante ◽  
G. C. Rossi
Keyword(s):  
Ab Initio ◽  
Binding Sites ◽  
Terminal Region ◽  
Test Case ◽  
Ab Initio Simulations

scholarly journals Deprotonation of resorcinarenes and novel ammonium salt complexes

2014 ◽  
Vol 70 (a1) ◽  
pp. C678-C678
Author(s):  
Ngong Beyeh ◽  
Arto Valkonen ◽  
Fanfang Pan ◽  
Kari Rissanen
Keyword(s):  
Hydrogen Bonds ◽  
Binding Sites ◽  
Molecular Complexes ◽  
Ammonium Salts ◽  
Hydroxyl Groups ◽  
Binding Modes ◽  
Intermolecular Hydrogen Bonds ◽  
Guest Molecules ◽  
Cone Conformation ◽  
Intramolecular Hydrogen

The bowl shape cavity of resorcinarenes usually stabilized by four intramolecular hydrogen bonds offers an interesting array of binding modes such as C–H...π and cation...π interactions to recognize a variety of guests. The multiple hydroxyl groups can participate in a series of intermolecular hydrogen bonds with guest molecules. This unique cone conformation of resorcinarenes has led to the synthesis of many receptors with convergent arrangement of binding sites suitable for molecular recognition in many applications. Unfunctionalized resorcinarenes are known to easily form molecular complexes with guests of varying shapes and sizes. Amines are very common bases used in many catalytic processes. A good example is the use of amines as bases in the alkylation and acylation of resorcinarenes leading to cavitands, carcerands, hemicarcerands and velcrands. The use of amines in such reactions is to deprotonate the resorcinarene hydroxyl groups, hence facilitating the alkylation and acylation processes. The subsequently protonated ammonium cation then forms interesting supramolecular complexes with the anionic and dianionic resorcinarenes. Furthermore, secondary and tertiary ammonium salts possess hydrogen bond donating -NH2 and -NH respectively and these can further enhance their complexation through intermolecular hydrogen bonds. Here we present our recent examples of supramolecular assemblies resulting from the deprotonation of resorcinarenes by mono- and dibasic amines. Also, our latest supramolecular co-crystals between resorcinarenes as the receptors and a series of secondary and tertiary mono- and diammonium cations are illustrated.

scholarly journals Alignment of caldesmon on the actin-tropomyosin filaments

1995 ◽  
Vol 309 (3) ◽  
pp. 951-957 ◽  
Author(s):  
T S Tsuruda ◽  
M H Watson ◽  
D B Foster ◽  
J J J C Lin ◽  
A S Mak
Keyword(s):  
Escherichia Coli ◽  
Smooth Muscle ◽  
Binding Site ◽  
Actin Filament ◽  
Binding Sites ◽  
Human Fibroblast ◽  
Thin Filament ◽  
Terminal Region ◽  
Terminal Domain ◽  
Terminal Fragment

We have reported previously that each smooth-muscle caldesmon binds predominantly to a region within residues 142-227 of tropomyosin, but a weaker binding site also exists at the N-terminal region of tropomyosin [Watson, Kuhn, Novy, Lin and Mak (1990) J. Biol. Chem. 265, 18860-18866]. In view of recent evidence for the presence of tropomyosin-binding sites at both the N- and C-terminal domains of caldesmon, we have studied the binding of the N- and C-terminal fragments of human fibroblast caldesmon expressed in Escherichia coli to tropomyosin and its CNBr fragments. The N-terminal fragment, CaD40 (residues 1-152), binds tropomyosin, but the interaction is mostly abolished in the presence of actin. CaD40 binds strongly to Cn1B(142-281) of tropomyosin, but weakly to Cn1A(11-127). The C-terminal fragment, CaD39, which corresponds to residues 443-736 of gizzard caldesmon, binds tropomyosin, and the interaction is enhanced by actin. CaD39 binds to both Cn1A(11-127) and Cn1B(142-281) of tropomyosin. Our results suggest that the N-terminal domain of caldesmon interacts with the C-terminal half of one tropomyosin molecule, whereas the C-terminal domain binds to both N- and C-terminal regions of the adjacent tropomyosin molecule along the actin filament. In addition, the binding of the N-terminal domain of caldesmon to the actin-tropomyosin filament is weak, which may allow this domain to project off the thin filament to interact with myosin.

scholarly journals Recruitment of CBP/p300, TATA-Binding Protein, and S8 to Distinct Regions at the N Terminus of Adenovirus E1A

2005 ◽  
Vol 79 (9) ◽  
pp. 5594-5605 ◽  
Author(s):  
Mozhgan Rasti ◽  
Roger J. A. Grand ◽  
Joe S. Mymryk ◽  
Phillip H. Gallimore ◽  
Andrew S. Turnell
Keyword(s):  
Transcriptional Activation ◽  
Binding Sites ◽  
Transcriptional Repression ◽  
Binding Protein ◽  
Cellular Transformation ◽  
Tata Binding Protein ◽  
Transformation Process ◽  
Terminal Region ◽  
Site Directed Mutagenesis

ABSTRACT The N-terminal region of the adenovirus (Ad) 12S E1A gene product targets several cellular proteins that are essential for the induction of S phase, cellular immortalization, cellular transformation, transcriptional repression, and transcriptional activation. The precise binding sites for these proteins, however, remain to be resolved. We therefore undertook an extensive site-directed mutagenesis approach to generate specific point mutants and to precisely map the binding sites for CBP, p300, TATA-binding protein (TBP), S4, S8, hGcn5, P/CAF, and Ran within the first 30 amino acids of the Ad5 12S E1A protein. We determined that although common residues within the N-terminal region can form partial binding sites for these proteins, point mutants were also generated that could discriminate between binding sites. These data indicate that AdE1A can target each of these proteins individually through distinct binding sites. It was evident, however, that the mutation of specific hydrophobic residues typically had the greatest effect upon AdE1A's ability to bind individual partners. Indeed, the mutation of L at positions 19 and 20 eliminated the ability of AdE1A to interact with any of the N-terminal binding proteins studied here. Interestingly, although TBP and S8 or CBP/p300 can exist as functional complexes, RNA interference revealed that the recruitment of either TBP, S8, or CBP/p300 to AdE1A was not dependent upon the expression of the other proteins. These data further indicate that AdE1A can target individual partner proteins in vivo and that it does not necessarily recruit these proteins indirectly as components of larger macromolecular complexes. Finally, we took advantage of the fine-mapping data to ascertain which proteins were targeted during the transformation process. Consistent with previous studies, CBP/p300 was found to be targeted by AdE1A during this process, although our data suggest that binding to other N-terminal proteins is also important for transformation.

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