Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Opsins”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed2006

Mouse opsin promoter-directed Cre recombinase expression in transgenic mice.

PURPOSE: Gene inactivation with homologous recombination in mice is a widely used tool to study gene function. However, many proteins play essential roles in a number of tissues and germline gene inactivation often results in embryonic lethality. To overcome this limitation and to dissect the functions of essential genes beyond embryonic development, we generated mouse rod opsin promoter-controlled cre transgenic mice with a goal of obtaining transgenic lines with a range of Cre activity in rod photoreceptors. METHODS: Transgenic mice expressing Cre recombinase directed by a long or short mouse opsin promoter were generated. Candidate Cre-expressing lines were identified with RT-PCR and Western blot analysis. Potentially useful Cre-expressing lines were characterized further with immunohistochemistry, PCR, and functional analysis using a Cre-activatable lacZ reporter mouse strain (R26R) to determine temporal and spatial patterns of Cre expression. Retinal function and morphology in these mouse lines were analyzed with electroretinography (ERG) and light microscopy of hematoxylin and eosin stained retinal sections. RESULTS: Transgenic mice expressing Cre in rod photoreceptors were generated. Characterization of candidate photoreceptor-specific Cre mice using immunohistochemistry and functional assays demonstrated that an efficient Cre-mediated recombination occurred in rod photoreceptor cells in one mouse line and a mosaic Cre-mediated recombination occurred in rod photoreceptors and rod bipolar cells in another mouse line. Further analysis of these mice with ERG and morphological examination suggested that the retinas of eight-month-old adults were normal. CONCLUSIONS: We have generated transgenic mice expressing Cre recombinase in rod photoreceptors. One transgenic mouse line was capable of carrying out efficient Cre-mediated recombination in rod photoreceptors. Another transgenic mouse line was capable of carrying out mosaic Cre-mediated recombination in rod photoreceptors and bipolar cells across the whole retina. These mice will be useful tools for Cre/lox-based gene activation and inactivation, as well as genetic mosaics, in rod photoreceptors and rod bipolar cells.

Animals↗
PubMed1990

Opsin of Calliphora peripheral photoreceptors R1-6. Homology with Drosophila Rh1 and posttranslational processing.

The rhodopsin and metarhodopsin states of two very distantly related fly species (Calliphora and Drosophila) are found to exhibit no species-specific differences in their absorbance spectra. Isolation and characterization of cDNAs encoding the major opsin of Calliphora reveal a high (86%) degree of amino acid identity with the corresponding Drosophila visual pigment. Completely conserved is the third cytoplasmic loop which displays the major structural differences with the vertebrate photopigments. Other conserved motifs are six potential phosphorylation sites in the C-terminal region of the molecule and two potential glycosylation sites in the extracellular domains at positions Asn18 and Asn194, respectively. Interestingly, unlike vertebrate visual pigments, only newly synthesized fly opsin is N-glycosylated, while the mature protein is not. The conserved structure of the cytoplasmic loops suggests that the molecular mechanism for the activation of the transduction cascade is precisely the same in Drosophila and in Calliphora. Thus, data obtained by investigating the biochemistry of rhodopsin-related processes in larger flies may be integrated with the results of genetic experiments in Drosophila into a common model of invertebrate phototransduction.

Amino Acid Sequence↗
PubMed1991

Characterization of developmentally regulated and retina-specific nuclear protein binding to a site in the upstream region of the rat opsin gene.

DNase I protection and gel retardation assays have identified a sequence 5' to the transcription start site of the rat opsin gene that interacts with nuclear proteins from mammalian retinas but not from a variety of other neural and non-neural tissues. Following sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transfer to nitrocellulose the protein(s) responsible for this binding were identified with an oligonucleotide probe and were found to migrate with an apparent molecular size of 40 kilodaltons. The binding complex eluted from fast protein liquid chromatography gel filtration as a peak centered at 100 kilodaltons, suggesting the presence of more than one subunit. Binding activity could be detected in postnatal day 1 retinal extracts and increased over the next 2 weeks of development, a time course coincident with opsin gene expression and maturation of rod photoreceptors. Synthetic oligonucleotides with altered sequences showed that the binding was dependent upon residues in a CTAAT motif and was facilitated by surrounding GGCCCC sequences. The specificity of the binding interaction was measured by inhibition of complex formation in a gel retardation assay. The unaltered sequence was over 2 orders of magnitude more effective at inhibiting complex formation than either an unrelated DNA sequence or a concensus sequence corresponding to a known CCAAT box binding protein NF1.

Animals↗
PubMed1989

Opsin- and S-antigen-like immunoreactions in photoreceptors of the tree shrew retina.

In the tree shrew retina individual rod and cone photoreceptors can be readily identified and quantified because their perikarya are arranged in a single layer. This retina is therefore an ideal system for testing the specificity of photoreceptor-directed antibodies. Here we describe the staining properties of polyclonal antibodies against (rhod)opsin and retinal S-antigen in the tree shrew retina. The (rhod)opsin antibody exclusively and completely labelled the rod population. The antibody against S-antigen also labelled all rods and, in addition, a regularly arrayed subpopulation of cones, which we argue to be the blue-sensitive cones. In the context of our findings, the labelling of pinealocytes with these antibodies is discussed.

Animals↗
PubMed1987

Selective destruction of photoreceptor cells by anti-opsin antibodies.

This article reports that cultured photoreceptor cells are selectively vulnerable to complement-mediated lysis by antiopsin antisera. The study has been carried out using a culture system that permits the growth of embryonic retinal neurons and photoreceptor cells in the absence of glial, pigment epithelial, connective, or endothelial cell contamination. Exposure of these cultures to an antiopsin antiserum in the presence of complement results in the lysis of 85% of the photoreceptor cells, without extensive loss of neurons. Photoreceptor lysis by the antibody is dose-dependent and specific, as demonstrated by the ability to block photoreceptor lysis by preincubation of the antiopsin antiserum with purified rhodopsin. Photoreceptor sensitivity to lysis by these antibodies develops in vitro in parallel with the appearance of immunocytochemically detectable opsin. Multipolar neurons (which do not contain opsin) are not affected by the treatment, as shown by microscopic analysis and determination of neuronal "markers" such as choline acetyltransferase and GABA high affinity uptake. These results show that antiopsin antibodies can cause selective photoreceptor degeneration. Moreover, this in vitro system appears useful as a bioassay to test a variety of possible mechanisms of retinal cell destruction which may be important in vivo. The results suggest also a mechanism for the generation of enriched retinal neuronal cultures by selective lysis of photoreceptor cells.

Animals↗
PubMed1988

[Synthesis of visual rhodopsin in a cell-free translation system. I. Influence of the structure of the synthetic bovine visual opsin mRNA on its translational efficiency].

Influence of structural changes in nontranslated regions and translation initiation site of the in vitro synthesized bovine opsin mRNA on its translational efficiency in the wheat germ cell-free system has been studied. It is shown that level of the opsin synthesis up to 30 micrograms per 1 ml of translational mixture can be attained by optimizing structure of 5'-nontranslated region.

Animals↗
PubMed1982

Immunoreactive opsin in the pineal organ of reptiles and birds.

The presence of opsin was investigated with light microscopic immunocytochemistry in pinealocytes of reptiles and birds (Emys orbicularis, Pseudemys scripta elegans, Lacerta agilis et viridis, Gallus domesticus, Columba livia, Melopsittacus undulatus, Serinus canaria, Taeniopyga punctate). The outer segments of pinealocytes selectively bound antiopsin antibody as revealed by indirect immunocytochemical techniques, indicating the occurrence of a rhodopsin-like photopigment in these structures. The results were compared with those obtained in retinal photoreceptors of the same species as well as in the pineal organ of fishes and amphibians (Cyprinus carpio, Carassius auratus, Rana esculenta). Corresponding to immunoreactive structures seen in the light microscope, we found typical outer segments on a large number of pinealocytes in most of the reptiles and birds studied. The presence of opsin in the numerous well developed pineal outer segments of these reptilian and avian species contradicts the earlier hypothesis on the gradual regression of pineal sensitive structures in the avian line of evolution.

Animals↗
PubMed1991

Distribution and morphology of human cone photoreceptors stained with anti-blue opsin.

Primate cones maximally sensitive to short wavelength light (blue cones) have been previously identified by using indirect methods. We stained 7 wholemounted human retinas obtained from 6 female donors, using an affinity purified antibody to a 19 amino acid peptide sequence at the N-terminus of blue opsin (Lerea et al., '89: Neuron 3:367-376), standard PAP immunocytochemistry, and controls. Cones were counted where all outer segments could be traced to inner segments and were measured where cells were well aligned vertically. We find that: (1) 7% of cones within 4 mm of the foveal center are labeled by antiblue opsin; (2) compared to neighboring red/green cones, blue cone inner segments are 10% taller, have a larger cross-sectional diameter near the junction with the outer segment, and a smaller diameter near the external limiting membrane, resulting in a more cylindrical shape, (3) foveal blue cones are sparse, irregularly spaced, and missing in a zone about 100 microns (0.35 degrees) in diameter near the site of peak cone density, (4) the highest densities of blue cones (greater than 2,000 cells/mm2) are found in a ring at 0.1-0.3 mm eccentricity, and (5) the shortest distances between neighboring cones are between blue and red/green cones, and the blue and red/green mosaics are statistically independent. These findings are consistent with psychophysical reports of foveal tritanopia and maximum sensitivity to blue light at 1 degree eccentricity. Blue cone spacing may limit resolution of the blue channel out to 20-30 degrees eccentricity. The blue and red/green mosaics appear to be formed by separate processes.

Adolescent↗
PubMed2001

Phylogenetic utility of the major opsin in bees (Hymenoptera: Apoidea): a reassessment.

Major opsin (LW Rh) DNA sequence has been reported to provide useful data for resolving phylogenetic relationships among tribes of corbiculate bees based on analyses of 502 bp of coding sequence. However, the corbiculate tribes are believed to be of Cretaceous age, and strong support for insect clades of this age from small data sets of nucleotide sequence data has rarely been demonstrated. To more critically assess opsin's phylogenetic utility we generated an expanded LW Rh data set by sequencing the same gene fragment from 52 additional bee species from 24 tribes and all six extant bee families. Analyses of this data set failed to provide substantial support for monophyly of corbiculate bees, for relationships among corbiculate tribes, or for most other well-established higher-level relationships among long-tongued bees. However, monophyly of nearly all genera and tribes is strongly supported, indicating that LW Rh provides useful phylogenetic signal at lower taxonomic levels. When our expanded LW Rh data set is combined with a morphological and behavioral data set for corbiculate bees, the results unambiguously support the traditional phylogeny of the corbiculate bee tribes: (Euglossini + (Bombini + (Meliponini + Apini))). This implies a single origin of advanced eusocial behavior among bees rather than dual origins, as proposed by several recent studies.

Animals↗
PubMed1980

Changes in the protonation state of bacterio-opsin during reconstitution of bacteriorhodopsin.

Protonation changes of the protein occur during the reconstitution of bacteriorhodopsin from bacterio-opsin and all-trans retinal in the purple membrane of Halobacterium halobium. The protonation changes are conveniently determined from measures of the pH changes after photoisomerisation of 9-cis retinal in apomembrane preparations, which induces the reconstitution. In addition, to the omega-amino group of the lysine which is involved in the condensation of retinal and bacterio-opsin, the dissociation equilibria of at least two other amino acid residues are changed during the reconstitution. The results are consistent with a proposed model of chromophore structure in which an interaction of the Schiff's base occurs with two protonable amino acid residues.

Apoproteins↗
PubMed1999

Conformational change in bacterio-opsin on binding to retinal.

The detailed mechanism of retinal binding to bacterio-opsin is important to understanding retinal pigment formation as well as to the process of membrane protein folding. We have measured the temperature dependence of bacteriorhodopsin formation from bacterio-opsin and all-trans retinal. An Arrhenius plot of the apparent second-order rate constants gives an activation energy of 11.6 +/- 0.7 kcal/mol and an activation entropy of -4 +/- 2 cal/mol deg. Comparison of the activation entropy to model compound reactions suggests that chromophore formation in bacteriorhodopsin involves a substantial protein conformational change. Cleavage of the polypeptide chain between residues 71 and 72 has little effect on the activation energy or entropy, indicating that the connecting loop between helices B and C is not involved in this conformational change.

Bacteriorhodopsins↗
PubMed1990

Solid-state NMR studies of the mechanism of the opsin shift in the visual pigment rhodopsin.

Solid-state 13C NMR spectra have been obtained of bovine rhodopsin and isorhodopsin regenerated with retinal selectively 13C labeled along the polyene chain. In rhodopsin, the chemical shifts for 13C-5, 13C-6, 13C-7, 13C-14, and 13C-15 correspond closely to the chemical shifts observed in the 11-cis protonated Schiff base (PSB) model compound. Differences in chemical shift relative to the 11-cis PSB chloride salt are observed for positions 8 through 13, with the largest deshielding (6.2 ppm) localized at position 13. The localized deshielding at C-13 supports previous models of the opsin shift in rhodopsin that place a protein perturbation in the vicinity of position 13. Spectra obtained of isorhodopsin regenerated with 13C-labeled 9-cis-retinals reveal large perturbations at 13C-7 and 13C-13. The similar deshielding of the 13C-13 resonance in both pigments supports the presence of a protein perturbation near position 13. However, the chemical shifts at positions 7 and 12 in isorhodopsin are not analogous to those observed in rhodopsin and suggest that the binding site interactions near these positions are different for the two pigments. The implications of these results for the mechanism of the opsin shift in these proteins are discussed.

Animals↗
PubMed1975

Synthesis of rhodopsin and opsin in vitro.

Isolated bovine retinas have been used to study the synthesis of rhodopsin and the renewal of photoreceptor rod outer segments. Both leucine and glucosamine served as radioactive tracers to follow rhodopsin synthesis. In both cases the rod outer segment preparations contained large amounts of labeled macromolecules chromatographically distinct from rhodopsin, the latter representing only about 10% of the high molecular weight labeled material. However, electrophoresis on polyacrylamide gels with sodium dodecyl sulfate indicated that as much as 60-68% of the radioactivity coincided with opsin, the apoprotein of rhodopsin. Treatment of labeled rod outer segments with 9-cis-retinal caused much of the non-rhodopsin label to be converted to isorhodopsin. After such treatment the fraction of the label in visual pigment rose from about 10 to 51% with leucine as the radioactive tracer and to 78% with glucosamine. Similar treatment of bleached outer segments labeled with leucine gave identical results with complete regeneration of isorhodopsin (lambda max 487 nm) which then accounted for 56% of the labeled macromolecules. No such conversion occurred in controls lacking 9-cis-retinal. Both 9-cis- and 11-cis-retinal were effective but all-trans-retinal was ineffective in producing the conversion. Under in vitro conditions opsin appears to be accumulated in the outer segment prior to the addition of retinal.

Animals↗
PubMed1983

Bacterio-opsin mutants of Halobacterium halobium.

The bacterio-opsin (bop) gene of Halobacterium halobium R1 has been cloned with about 40 kilobases of flanking genomic sequence. The 40-kilobase segment is derived from the (G+C)-rich fraction of the chromosome and is not homologous to the major (pHH1) or minor endogenous covalently closed circular DNA species of H. halobium. A 5.1-kilobase Pst I fragment containing the bop gene was subcloned in pBR322 and a partial restriction map was determined. Defined restriction fragments of this clone were used as probes to analyze the defects associated with the bop gene in 12 bacterio-opsin mutants. Eleven out of 12 of the mutants examined had inserts ranging from 350 to 3,000 base pairs either in the bop gene or up to 1,400 base pairs upstream. The positions of the inserts were localized to four regions in the 5.1-kilobase genomic fragment: within the gene (one mutant), in a region that overlaps the 5' end of the gene (seven mutants), and in two different upstream regions (three mutants). Two revertants of the mutant with the most distal insert had an additional insert in the same region. The polar effects of these inserts are discussed in terms of inactivation of a regulatory gene or disruption of part of a coordinately expressed operon. Given the defined nature of the bop mRNA-i.e., it has a 5' leader sequence of three ribonucleotides-these observations indicate that the bop mRNA might be processed from a large mRNA transcript.

Journal Article↗
PubMed1979

The gecko visual pigments. The behavior of opsin.

The 521-pigment extracted out of the retina of the Tokay gecko has the typical stereospecificity of the vertebrate visual pigments. This is true for the pigment in the chloride-depleted, "blue-shifted" state as well as for the normal pigment with added chloride. While in the chloride-deficient state, pigment regeneration occurred with both 11-cis- and 9-cis-retinals and the regenerated photopigments were also in the blue-shifted, chloride-depleted state. As with the native pigment, these regenerated pigments were bathochromically shifted to their normal positions by the addition of chloride. Chloride-deficient opsin by itself also responded to chloride for the pigment regenerated with 11-cis-retinal from such chloride-treated opsin was in the normal 521-position. Regeneration was always rapid, reaching completion in less than 5 min, and was significantly faster than for cow rhodopsin regenerating under the same conditions. This rapid rate was found with or without chloride, with both 11-cis- and 9-cis-retinals and in the presence of the sulfhydryl poison, p-hydroxymercuribenzoate (PMB). Like the native chloride-deficient pigment, the regenerated chloride-depleted photopigments responded to PMB by a blue shift beyond the position of the chloride-deficient state. The addition of chloride to these "poisoned" regenerated pigments caused a bathochromic shift of such magnitude as to indicate a repair of both the PMB and chloride-deficient blue shift. In this discussion the possible implications of these results to phylogenetic considerations are considered as well as to some molecular properties of the 521-pigment.

Animals↗
PubMed1976

Opsin structure probed by raman spectroscopy of photoreceptor membranes.

The first nonresonance Raman spectra of photoreceptor membranes are presented. Information about the membrane protein, opsin, and the membrane phospholipids can be deduced. Opsin appears to contain alpha-helical structure but little beta structure. The tyrosine residues are predominantly hydrogen bonded, and disulfide bonds, if they are present, are not in the normal gauche-gauche configuration.

Animals↗
PubMed1987

Structure-function studies on bacteriorhodopsin. III. Total synthesis of a gene for bacterio-opsin and its expression in Escherichia coli.

We have chemically synthesized a DNA duplex of 757 base pairs which encodes the entire protein sequence of mature bacterio-opsin of Halobacterium halobium. The main aim of the synthesis was to facilitate site-specific mutagenesis in all parts of the gene by replacement of short restriction fragments by their counterparts containing the required nucleotide changes. Therefore, 30 unique restriction sites that are fairly evenly spaced were introduced in the synthetic DNA. A total of 28 oligonucleotides ranging in size from 21 to 69 nucleotides were synthesized corresponding to both strands. The entire gene was assembled from four synthetic fragments of 25, 268, 219, and 245 base pairs. The correctness of the nucleotide sequence was confirmed by sequencing the fragments as well as the complete gene. When expressed under the control of PL promoter in Escherichia coli, the synthetic and the native genes gave similar amounts of bacterio-opsin. Attempts to increase expression of the synthetic gene by introducing codons that are preferred in E. coli or by introduction of a synthetic transcription terminator were without significant effect.

Bacteriorhodopsins↗