The structure of rice weevil pectin methylesterase.

Rice weevils (Sitophilus oryzae) use a pectin methylesterase (EC 3.1.1.

Atomic resolution studies of carbonic anhydrase II.

Carbonic anhydrase has been well studied structurally and functionally owing to its importance in respiration. A large number of X-ray crystallographic structures of carbonic anhydrase and its inhibitor complexes have been determined, some at atomic resolution. Structure determination of a sulfonamide-containing inhibitor complex has been carried out and the structure was refined at 0.

Release of 11-cis-retinal from cellular retinaldehyde-binding protein by acidic lipids.

Purpose: To determine molecular mechanisms for the release of 11-cis-retinal from the binding pocket of cellular retinaldehyde-binding protein (CRALBP).

Methods: Binding of CRALBP to lipid surfaces was assessed with a lipid-immunoblot assay. Lipids were presented to CRALBP as small unilamellar vesicles (SUVs) consisting of phosphatidylcholine (PC) plus other lipids.

Reprint of "Crystal packing analysis of Rhodopsin crystals" [J. Struct. Biol. 158 (2007) 455-462].

Oligomerization has been proposed as one of several mechanisms to regulate the activity of G protein-coupled receptors (GPCRs), but little is known about the structure of GPCR oligomers. Crystallographic analyses of two new crystal forms of rhodopsin reveal an interaction surface which may be involved in the formation of functional dimers or oligomers. New crystallization conditions lead to the formation of two crystal forms with similar rhodopsin-rhodopsin interactions, but changes in the crystal lattice are induced by the addition of different surfactant additives.

Crystal packing analysis of Rhodopsin crystals.

Oligomerization has been proposed as one of several mechanisms to regulate the activity of G protein-coupled receptors (GPCRs), but little is known about the structure of GPCR oligomers. Crystallographic analyses of two new crystal forms of rhodopsin reveal an interaction surface which may be involved in the formation of functional dimers or oligomers. New crystallization conditions lead to the formation of two crystal forms with similar rhodopsin-rhodopsin interactions, but changes in the crystal lattice are induced by the addition of different surfactant additives.

Structural insights into the cellular retinaldehyde-binding protein (CRALBP).

Cellular retinaldehyde-binding protein (CRALBP) is an essential protein in the human visual cycle without a known three-dimensional structure. Previous studies associate retinal pathologies to specific mutations in the CRALBP protein. Here we use homology modeling and molecular dynamics methods to investigate the structural mechanisms by which CRALBP functions in the visual cycle.

Rhodopsin: a structural primer for G-protein coupled receptors.

An overview of the rhodopsin crystal structure provides a structural basis for understanding the structures and functions of other G-protein coupled receptors (GPCRs). All of the structural details observed to date for rhodopsin will not necessarily carry over to other GPCRs, but major features such as the arrangement of the seven transmembrane helices, the retinal/ligand binding site, the D(E)RY and NPXXY sequence and structural motifs, and the bent helices are likely characteristics of the GPCRs most closely related to rhodopsin. A general view of these structural features is presented here.

Identification of CRALBP ligand interactions by photoaffinity labeling, hydrogen/deuterium exchange, and structural modeling.

Cellular retinaldehyde-binding protein (CRALBP) functions in the retinal pigment epithelium (RPE) as an acceptor of 11-cis-retinol in the isomerization step of the rod visual cycle and as a substrate carrier for 11-cis-retinol dehydrogenase. Toward a better understanding of CRALBP function, the ligand binding cavity in human recombinant CRALBP (rCRALBP) was characterized by photoaffinity labeling with 3-diazo-4-keto-11-cis-retinal and by high resolution mass spectrometric topological analyses. Eight photoaffinity-modified residues were identified in rCRALBP by liquid chromatography tandem mass spectrometry, including Tyr(179), Phe(197), Cys(198), Met(208), Lys(221), Met(222), Val(223), and Met(225).

Evolutionary analysis of rhodopsin and cone pigments: connecting the three-dimensional structure with spectral tuning and signal transfer.

Extensive sequence data and structural sampling of expressed proteins from different species lead to the idea that entire molecules or specific domain folds belong to large superfamilies of proteins. A subset of G protein-coupled receptors, one of the largest families involved in cellular signaling, rod and cone opsins are involved in phototransduction in photoreceptor cells. Here, the evolutionary analysis of opsin sequences and structures predicts key residues involved in the transmission of the signal from the binding site of the chromophore to the cytoplasmic surface and residues that are involved in the spectral tuning of opsins to short wavelengths of light.

Problem-oriented instruction as a predictor of success in early psychiatric interviewing.

Of 77 second-year medical students, the 27 who were randomly assigned to problem-oriented instruction (POI) in interviewing skills rated themselves as better prepared and more successful in interviews of psychiatric patients, compared with students receiving lecture only or no classroom instruction in interviewing skills. POI-trained students also rated themselves as better in focusing on nonverbal aspects, effective questioning, and exploring feelings. The POI involved hierarchically organized, skills-focused role-plays in which students rotated through the roles of "doctor," "patient," and "observer.

Ligand channeling within a G-protein-coupled receptor. The entry and exit of retinals in native opsin.

Deactivation of light-activated rhodopsin (metarhodopsin II) involves, after rhodopsin kinase and arrestin interactions, the hydrolysis of the covalent bond of all-trans-retinal to the apoprotein. Although the long-lived storage form metarhodopsin III is transiently formed, all-trans-retinal is eventually released from the active site. Here we address the question of whether the release results in a retinal that is freely diffusible in the lipid phase of the photoreceptor membrane.

The crystallographic model of rhodopsin and its use in studies of other G protein-coupled receptors.

G protein-coupled receptors (GPCRs) are integral membrane proteins that respond to environmental signals and initiate signal transduction pathways activating cellular processes. Rhodopsin is a GPCR found in rod cells in retina where it functions as a photopigment. Its molecular structure is known from cryo-electron microscopic and X-ray crystallographic studies, and this has reshaped many structure/function questions important in vision science.

G protein-coupled receptor rhodopsin: a prospectus.

Rhodopsin is a retinal photoreceptor protein of bipartite structure consisting of the transmembrane protein opsin and a light-sensitive chromophore 11-cis-retinal, linked to opsin via a protonated Schiff base. Studies on rhodopsin have unveiled many structural and functional features that are common to a large and pharmacologically important group of proteins from the G protein-coupled receptor (GPCR) superfamily, of which rhodopsin is the best-studied member. In this work, we focus on structural features of rhodopsin as revealed by many biochemical and structural investigations.

Crystal structures and increased stabilization of the protein G variants with switched folding pathways NuG1 and NuG2.

We recently described two protein G variants (NuG1 and NuG2) with redesigned first hairpins that were almost twice as stable, folded 100-fold faster, and had a switched folding mechanism relative to the wild-type protein. To test the structural accuracy of our design algorithm and to provide insights to the dramatic changes in the kinetics and thermodynamics of folding, we have now determined the crystal structures of NuG1 and NuG2 to 1.8 A and 1.