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Influence of secondary structure segments of Bacillus subtilis CotX protein on its coat localisation

100%

Potocki W. , Kazmierkiewicz R. , Obuchowski M.

2017

tom 56

nr 1

Molecular modelling of the vasopressin V2 receptor-antagonist interactions

100%

Czaplewski C. , Kazmierkiewicz R. , Ciarkowski J.

nr 1

We predict some essential interactions between the V2 vasopressin renal receptor (V2R) and its selective peptide antagonist desGly9-[Mca1,D-Ile2,Ile4]AVP, and compare these predictions with the earlier ones for the non-peptide OPC-36120 antagonist- and the [Arg8]vasopressin (AVP) agonist-V2 receptor interactions. V2R controls antidiuresis in mammals and belongs to the superfamily of the heptahelical transmembrane (7TM) G protein-coupled receptors (GPCR)s. V2R was built, the ligands docked and the structures relaxed using advanced molecular modeling techniques. Both the agonist and the antagonists (no matter whether of peptide- or non-peptide type) appear to prefer a common V2R compartment for docking. The receptor amino-acid residues, potentially important in ligand binding, are mainly in the TM3-TM7 helices. A few of these residues are invariant for the whole GPCR superfamily while most of them are conserved in the subfamily of neurohypophyseal receptors, to which V2R belongs. Some of the equivalent residues in a related V1a receptor have been earlier reported as critical for the ligand affinity.

The influence of modification at position 2 on the side-chain conformation in oxytocin analogs

100%

Smiech B. , Kazmierkiewicz R. , Lammek B.

tom 53

nr 1

The nonapeptide oxytocin (OT) is used in medicine to help begin and/or continue childbirth. Its analogs can be also used to control bleeding following fetus delivery. The main function of oxytocin is to stimulate contraction of uterus smooth muscle and the smooth muscle of mammary glands, thus regulating lactation. This paper describes theoretical simulations of the distribution of the torsional angles χ1 in the non-standard methylated phenylalanine residues of three oxytocin analogs: [(Phe)2o-Me]OT, [(Phe)2m-Me]OT, [(Phe)2p-Me]OT. The conformations of the oxytocin analogs were studied both in vacuum and in solution. We found some correlations between the biological activity of the considered peptides and the side-chain conformations of amino-acid residues 2 and 8.

Signal transmission via G protein-coupled receptors in the light of rhodopsin structure determination

88%

Ciarkowski J. , Drabik P. , Gieldon A. , Kazmierkiewicz R. , Slusarz R.

Acta Biochimica Polonica

2001

tom 48

nr 4

G protein-coupled receptors (GPCRs) transducing diverse external signals to cells via activation of heterotrimeric GTP-binding (G) proteins, estimated to mediate actions of 60% of drugs, had been resistant to structure determination until summer 2000. The first atomic-resolution experimental structure of a GPCR, that of dark (inactive) rhodopsin, thus provides a trustworthy 3D prototype for antagonist-bound forms of this huge family of proteins. In this work, our former theoretical GPCR models are evaluated against the new experimental template. Subsequently, a working hypothesis regarding the signal transduction mechanism by GPCRs is presented.