Molecular characterization of two G protein-coupled receptor splice variants as FLP2 receptors in Caenorhabditis elegans

Two alternatively spliced Caenorhabditis elegans G protein-coupled receptors, T19F4.1a and T19F4.1b, were cloned and functionally characterized. The T19F4.1b receptor protein is 30 amino acids longer than T19F4.1a, and the difference in amino acid constitution is exclusively conferred to the intracellular C-terminal region, suggesting a potential difference in G protein-coupling specificity. Following cloning of the receptor cDNAs into the pcDNA3 vector and stable or transient transfection into Chinese hamster ovary cells, the aequorin bioluminescence/Ca2+ assay was used to investigate receptor activation. This is the first report of the construction of a cell line stably expressing a C elegans neuropeptide receptor. Our experiments identified both receptors as being cognate receptors for two FMRFamide-related peptides encoded by the flp-2 precursor: SPREPIRFamide (FLP2-A) and LRGEPIRFamide (FLP2-B). Pharmacological profiling using truncated forms of FLP2-A and -B revealed that the active core of both peptides is EPIRFamide. Screening of peptides encoded by other flps did not result in a significant activation of the receptor. In contrast to other C elegans receptors tested in heterologous expression systems, the functional activation of both T19F4.1a and T19F4.1b was not temperature-dependent. Screening in cells lacking the promiscuous G,16 suggests that T19F4.1a and b are both linked to the G(q) pathway. (c) 2005 Elsevier Inc. All rights reserved.status: publishe

Iterative learning control in high-performance motion systems:from theory to implementation

Iterative learning control (ILC) enables a perfect compensation for systems that perform the same task over and over again. The aim of this paper is to demonstrate practical applicability of two various state-of-the-art ILC algorithms to point-to-point positioning systems. A simple Frequency domain ILC approach is exploited focusing on systems with exactly repeating motion tasks. Furthermore, flexible ILC is employed to enable learning also for non-repeating tasks. Particular steps providing a seamless transfer from theory and algorithms to practical implementation in a real-time environment by means of industrial-grade SW and HW are given. They may serve as a practical example of a workflow suitable for a wide range of motion control applications. Potential benefits of the learning-type control in comparison with conventional feedback and feedforward control are discussed as well.</p

G protein-coupled receptors in invertebrates: A state of the art

G protein-coupled receptors (GPCRs) constitute one of the largest and most ancient superfamilies of membrane-spanning proteins. We focus on neuropeptide GPCRs, in particular on those of invertebrates. In general, such receptors mediate the responses of signaling molecules that constitute the highest hierarchical position in the regulation of physiological processes. Until recently, only a few of these receptors were identified in invertebrates. However, the availability of a plethora of genomic information has boosted the discovery of novel members in several invertebrate species, such as Drosophila, in which 18 neuropeptide GPCRs have been characterized. The finalization of genomic projects in other invertebrates will lead to a similar expansion of GPCR understanding. Many new insights regarding neuropeptide regulation have followed from the discovery of their cognate receptors. Furthermore, information on GPCR signaling is still fragmentary and the elucidation of these pathways in model insects such as Drosophila will lead to further insights in other species, including mammals. In this review we present the current status of what is known about invertebrate GPCRs, discuss some novel perceptions that follow from the identified members, and, finally, present some future prospects.status: publishe

Characterization of the short neuropeptide F receptor from Drosophila melanogaster

A seven transmembrane G-protein coupled receptor has been cloned from Drosophila melanogaster. This receptor shows structural similarities to vertebrate Neuropeptide Y-2 receptors and is activated by endogenous Drosophila peptides, recently designated as short neuropeptide Fs (sNPFs). sNPFs have so far been found in neuroendocrine tissues of four other insect species and of the horseshoe crab. In locusts, they accelerate ovarian maturation, and in mosquitoes, they inhibit host-seeking behavior. Expression analysis by RT-PCR shows that the sNPF receptor (Drm-sNPF-R) is present in several tissues (brain, gut, Malpighian tubules and fat body) from Drosophila larvae as well as in ovaries of adult females. All 4 Drosophila sNPFs clearly elicited a calcium response in receptor expressing mammalian Chinese hamster ovary cells. The response is dose-dependent and appeared to be very,specific. The short NPF receptor was not activated by any of the other tested arthropod peptides, not even by FMRFamide-related peptides (also ending in RFamide), indicating that the Arg residue at position 4 from the amidated C-terminus appears to be crucial for the response elicited by the sNPFs (C) 2002 Elsevier Science (USA). All rights reserved.status: publishe

Postgenomic characterization of G-protein-coupled receptors

G-protein-coupled receptors (GPCRs) constitute one of the largest families of membrane-spanning proteins. Their importance in drug development has been proven over and over again. Therefore, they remain one of the most significant groups of molecules to be characterized. In the postgenomic era, the methods used for the characterization of GPCRs have dramatically changed: the predicted orphan receptors are now often used to ascertain the ligands (reverse pharmacology), whereas, in the past, the bioactive ligand was used to identify the receptor (classic approach). in this review, we will give an overview of the recent postgenomic functional assays that are frequently used to link the orphan GPCR of both vertebrate and invertebrate organisms with their ligands.status: publishe

Isolation, identification, and synthesis of a disulfated sulfakinin from the central nervous system of an arthropod, the white shrimp Litopenaeus vannamei

Two myotropic peptides displaying tyrosyl sulfation have been isolated from an extract of central nervous systems (brain, suboesophageal ganglion, thoracic ganglia, and ventral nerve cord) of the white shrimp Litopenaeus cannamei, Both peptides were identified by mass spectrometry and belong to the sulfakinin family of neuropeptides, which are characterized by the C-terminal hexapeptide Y(SO3H)GHMRF-NH2 preceded by two acidic amino acid residues, Pev-SK1 (AGGSGGVGGEY(SO3H)DDY (SO3H)GH(L/I) RF-NH2) has two sulfated tyrosyl residues and a unique (L/I) for M substitution in the C-terminal sequence. Pev-SK 2 (pQFDEY(SO3H)GHMRF-NH2) fully complies with the typical sulfakinin Core sequence and is blocked by a pyroglutamyl residue. Synthetic analogs (sulfated and unsulfated) were synthesized and the tyrosyl sulfations were confirmed by myotropic activity studies and co-elution with the native fractions. Pev-SK I is the first disulfated neuropeptide elucidated in the phylum of the arthropoda, with the only other reported disulfated neuropeptide. called cionin. found in a protochordate. The similarities in amino acid sequence and posttranslational modifications of the crustacean sulfakinins and protochordate cionin provide further evidence for the hypothesis stating that gastrin/CCK. cionin, and sulfakinins originate from a common ancestral gastrin/CCK-like peptide. (C) 2002 Elsevier Science (USA). All rights reserved.status: publishe

In situ methanol adsorption on aluminum oxide monitored by a combined ORP-EIS and ATR-FTIR Kretschmann setup

A common approach to investigate chemical interactions at the polymer/metal oxide interface is by monitoring ultrathin polymer films onto a metal oxide substrate by a variety of surface analysis techniques. The deposition of this nanometer-thin overlayer is frequently carried out by reactive adsorption from dilute polymer solutions. However, the influence of the solvent on the metal oxide chemistry is seldom taken into account in interface studies. The overall amount of available adsorption sites on the metal oxide surface might decrease due to competing adsorption of the solvent and the polymer adsorbate. Therefore, in this work, the adsorption of a common organic solvent (methanol) onto a physical vapor-deposited aluminum oxide surface is monitored in situ by an integrated attenuated total reflectance Fourier transform infrared spectroscopy in the Kretschmann geometry and odd random phase multisine electrochemical impedance spectroscopy system. It is shown that methanol immediately physisorbs onto the aluminum oxide surface and replaces the initial adventitious carbon layer. This process is followed by methanol chemisorbing onto the oxide surface to form methoxide species at the liquid/solid interface. Additionally, chemisorption is validated ex situ by X-ray photoelectron spectroscopy.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.(OLD) MSE-