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At least 217 records · Page 12Linked to original sources
PubMed2003

Expression of AMPA-type glutamate receptor subunit (GluR2) in ON-bipolar neurons in the rat retina.

The role of glutamate receptors (GluR) in the signal pathways of the retina is widely recognized. Photoreceptors make synaptic contact with functionally different classes of bipolar cells. The OFF-type bipolar cells mediate light offset-evoked responses and use ionotropic alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA)- or kainate-type GluRs, whereas bipolars involved in the ON-pathway use the metabotropic GluR6. This dichotomy predicts a defined expression pattern of AMPA-type GluRs and mGluR6 in bipolar cell classes. This hypothesis was tested by performing immunocytochemical double labeling studies combining GluR-specific antibodies with markers specific for the diverse bipolar cell populations in the rat retina. AMPA-type receptors are composed of combinations of four types of subunits, GluR1-4. GluR1 is expressed by a few somata in the outer part of the inner nuclear layer (INL). Sparse colocalization with any of the bipolar markers used could be established. In contrast, GluR2 is expressed by many of the somata in the outer zone of the INL. At the transcript level, in situ hybridizations demonstrated abundant GluR2 expression over the complete width of the INL. In contrast to our expectations, approximately 70% of the somata labeled by the rod ON-bipolar markers protein kinase C (PKC) or Goalpha, colocalized with GluR2. Approximately 90% of the OFF-type bipolar cells, identified as recoverin-positive, showed GluR2 immunoreactivity. At least 40% of the somata that were mGluR6-immunoreactive, a both rod and cone ON-type bipolar marker, were GluR2-immunopositive. Ultrastructurally, examples were observed of GluR2 localization in bipolar processes with labeling outside the actual compartment associated with the synaptic complex of the rod terminal. No specific antibody was available against GluR3, but 74% of the PKC-positive cells were GluR2/3-positive. GluR4 did not show a somatic localization making double labeling impossible. On the basis of these results, we conclude that ionotropic GluRs are expressed by rod ON-type bipolar cells (PKC- or Goalpha-immunoreactive), and by cone ON- and OFF-type bipolars based on a colocalization with nearly all of the present recoverin-positive somata. Our observations show that the functional dichotomy in ON- and OFF-type bipolars is not reflected in a matching expression pattern of ionotropic and metabotropic GluRs. This finding raises the intriguing possibility that the AMPA-type GluRs are, in an as yet unclear manner, involved in the ON signaling pathways of rods and cones.

Animals↗
PubMed2007

Photoreceptor proteins as cancer-retina antigens.

Melanocytes, melanoma and photoreceptor cells are of neuroectodermal origin and have a certain sensitivity to light. In this study, we present evidence for photoreceptor proteins that are responsible for visual transduction and its regulation function as a new class of cancer antigens in melanoma. Visual rhodopsin, transducin, cGMP-phosphodiesterase 6, cGMP-dependent channels, guanylyl cyclase, rhodopsin kinase, recoverin and arrestin are expressed in melanoma and can induce antibody responses in patients. Melanocytes also express mRNA of all photoreceptor genes besides transducin, but were devoid of the corresponding protein, which was tested for rhodopsin, cGMP-phosphodiesterase, guanylyl cyclase and recoverin. Furthermore, we show for the first time that some healthy tissues express mRNA of these genes, but never protein. Expression profiles and autoantibody responses were confirmed in the MT/ret and the HGF(tg)/Ink4a(-/-) transgenic mouse melanoma models. We propose a molecular transition of cancer-retina antigens from mRNA expression in melanocytes to protein expression in melanoma. Our work provides the basis for analyzing regulation of photoreceptor gene expression in normal and malignant cells as well as possible therapeutic tumor targeting using the newly defined class of cancer-retina antigens.

Animals↗
PubMed2004

Isolation of retinal progenitor cells from post-mortem human tissue and comparison with autologous brain progenitors.

The goal of the present study was threefold: to determine whether viable human retinal progenitor cells (hRPCs) could be obtained from cadaveric retinal tissue, to evaluate marker expression by these cells, and to compare hRPCs to human brain progenitor cells (hBPCs). Retinas were dissected from post-mortem premature infants, enzymatically dissociated, and grown in the presence of epidermal growth factor and basic fibroblast growth factor. The cells grew as suspended spheres or adherent monolayers, depending on culture conditions. Expanded populations were banked or harvested for analysis by RT-PCR, immunocytochemistry, and flow cytometry. hBPCs derived from forebrain specimens from the same donors were grown and used for RT-PCR. Post-mortem human retinal specimens yielded viable cultures that grew to confluence repeatedly, although not beyond 3 months. Cultured hRPCs expressed a range of markers consistent with CNS progenitor cells, including nestin, vimentin, Sox2, Ki-67, GD2 ganglioside, and CD15 (Lewis X), as well as the tetraspanins CD9 and CD81, CD95 (Fas), and MHC class I antigens. No MHC class II expression was detected. hRPCs, but not hBPCs, expressed Dach1, Pax6, Six3, Six6, and recoverin. Minority subpopulations of hRPCs and hBPCs expressed doublecortin, beta-III tubulin, and glial fibrillary acidic protein, which is consistent with increased lineage restriction in subsets of cultured cells. Viable progenitor cells can be cultured from the post-mortem retina of premature infants and exhibit a gene expression profile consistent with immature neuroepithelial cells. hRPCs can be distinguished from hBPC cultures by the expression of retinal specification genes and recoverin.

Antigens, Differentiation↗
PubMed2000

Purification of myristoylated and nonmyristoylated neuronal calcium sensor-1 using single-step hydrophobic interaction chromatography.

Neuronal calcium sensors (NCSs) belong to a family of Ca(2+)-binding proteins, which serve important functions in neurotransmission, and are highly conserved from yeast to humans. Overexpression of the neuronal calcium sensor-1, called frequenin in the fruit fly and in frog, increases the release of neurotransmitters. Studying the functional role of frequenin in mammals and understanding its structural dynamics is critically dependent on the availability of active purified protein. Neuronal calcium sensors like other members of the family share common structural features: they contain four EF-hands as potential binding sites for Ca(2+) and an N-terminal consensus sequence for myristoylation. Previously, recoverin, distantly related to NCSs, has been expressed and purified from Escherichia coli, involving a combination of different chromatographic steps. NCS-1 has earlier been purified adopting a two-step procedure used for recoverin purification. We have overexpressed NCS-1 from rat in its myristoylated and nonmyristoylated form in E. coli and purified it from crude lysates using a single-step hydrophobic interaction chromatography. The purified protein was identified by Western blotting and mass spectrometry and assayed for its ability to bind Ca(2+) using a Ca(2+) shift assay, terbium fluorescence, and Stains-all binding. The present protocol provides a rapid, more efficient and simplified, single-step method for purifying NCS-1 for structural and functional studies. This method can also be applied to purify related proteins of the superfamily.

Animals↗
PubMed2005

Changes in retinal neuronal populations in the DBA/2J mouse.

DBA/2J (D2) mice develop a form of progressive pigmentary glaucoma with increasing age. We have compared retinal cell populations of D2 mice with those in control C57BL/6J mice to provide information on retinal histopathology in the D2 mouse. The D2 mouse retina is characterized by a reduction in retinal thickness caused mainly by a thinning of the inner retinal layers. Immunocytochemical staining for specific inner retinal neuronal markers, viz., calbindin for horizontal cells; protein kinase C (PKC) and recoverin for bipolar cells, glycine, gamma-aminobutyric acid (GABA), choline acetyltransferase (ChAT), and nitric oxide synthase (NOS) for amacrine cells, and osteopontin (OPN) for ganglion cells, was performed to detect preferentially affected neurons in the D2 mouse retina. Calbindin, PKC, and recoverin immunoreactivities were not significantly altered. Amacrine cells immunoreactive for GABA, ChAT, and OPN were markedly decreased in number, whereas NOS-immunoreactive amacrine cells increased in number. However, no changes were observed in the population of glycine-immunoreactive amacrine cells. These findings indicate a significant loss of retinal ganglion and some amacrine cells, whereas glycinergic amacrine cells, horizontal, and bipolar cells are almost unaffected in the D2 mouse. The reduction in amacrine cells appears to be attributable to a loss of GABAergic and particularly cholinergic amacrine cells. The increase in nitrergic neurons with the consequent increase in NOS and NO may be important in the changes in the retinal organization that lead to glaucomain D2 mice. Thus, the D2 mouse retina represents a useful model for studying the pathogenesis of glaucoma and mechanisms of retinal neuronal death and for evaluating neuroprotection strategies.

Amacrine Cells↗
PubMed2005

Molecular imaging system for possible prediction of active retinopathy in patients with Diabetes mellitus.

OBJECTIVE: The deposition of advanced glycation end products is enhanced in Diabetes mellitus (DM) and has been linked to diabetic complications such as a microvascular disease. Glycated proteins have receptors on mononuclear blood cells (MBCs) and have been shown to generate reactive oxygen species altering gene expression and modifying cellular targets, such as endothelial cells. Retinal angiopathy is a frequently observed microvascular complication in DM-patients. Because of the central role of activated MBCs, we hypothesised a functional link between specific alterations in gene expression of MBCs, an increased activity of matrix proteases in serum, and the extent of retinal angiopathy in DM. MATERIAL AND METHODS: An appearance and proliferation index of diabetic retinopathy was evaluated in 38 DM-patients using fluorescein angiography. Alterations of gene transcription levels in MBCs were investigated using hybridisation of individual mRNA-pools to Atlas Array with a concomitant quantification of specific cDNAs by "Real-Time"-PCR. The activity of matrix metalloproteinases MMP-2 and MMP-9 in individual serum samples was measured by zymography combined with densitometric imaging system. RESULTS AND CONCLUSIONS: Hybridisation to Atlas Array of mRNA-pools isolated from MBCs revealed an enhanced expression of recoverin in DM-patients compared to the control group. "Real-Time"-PCR showed the highest recoverin levels in the DM-subgroup with a high proliferation index. MMP-2 activity was highly increased in 36% of all patients, and in 44, 44, and 19% of patients with proliferative retinopathy, advanced proliferative retinopathy, and no detectable proliferation respectively. In those 3 groups MMP-9 activity was highly increased in 56, 67, and 31% of patients respectively, and in 44% of all DM-patients. In contrast to patients with active proliferation, the simultaneous high activation of all three genes was not observed in patients without active proliferation. The ex vivo molecular imaging system developed in this work may be helpful for the prediction of active proliferative retinopathy in DM.

Diabetes Mellitus↗
PubMed1993

Neurocalcin family: a novel calcium-binding protein abundant in bovine central nervous system.

We purified and sequenced from bovine brain a novel calcium-binding protein. This protein which we named neurocalcin has 3 putative EF hand motifs and a close homology with recoverin which activates guanylate cyclase Ca2+ dependently. Neurocalcin has at least 6 isoforms and is expressed in the central nervous system (CNS), retina and adrenal gland. Considering unique distribution of neurocalcin, this protein may an important physiological role which differs from that of visinin or recoverin.

Amino Acid Sequence↗
PubMed1995

A calcineurin-B-encoding gene expressed during differentiation of the amoeboflagellate Naegleria gruberi contains two introns.

One of two similar genes in the unicellular eukaryote Naegleria gruberi is shown to encode calcineurin B (CnB), the regulatory subunit of calcium-calmodulin-regulated protein phosphatase 2B. Over a span of 156 amino acids, excluding divergent N-termini, the encoded sequence shows 62% identity with vertebrate CnB, and also shows sequence elements specific, among calcium-binding proteins, to CnB. In contrast, the sequence shows only 23% identity with N. gruberi flagellar calmodulin. CNB mRNA is readily detected in amoebae; its abundance increases fourfold during differentiation to flagellates, reaches a peak at 50-70 min, when flagella are forming, and then declines. A genomic clone matches an expressed cDNA, except that it is interrupted by two phase I introns. The position of one intron, which separates the divergent N-terminal domain from the four calcium-binding domains (EF hands), is shared with a yeast CNB gene; the other is located in the central helix between the two pairs of calcium-binding loops; features that support an ancient origin. These introns, the first found in protein-coding genes of Naegleria, are flanked by characteristic splice junction sequences. N. gruberi CnB also shares similarities with recoverins. The finding in a protist of a CNB gene that contains two introns separating functional domains, shares similarities to recoverins and shows increased expression during differentiation is provocative. If the phylogeny of major groups derived from ribosomal RNA is accepted, Naegleria is among the earliest branching eukaryotes known to contain canonical pre-mRNA introns.

Amino Acid Sequence↗
PubMed1993

Frequenin--a novel calcium-binding protein that modulates synaptic efficacy in the Drosophila nervous system.

The T(X;Y)V7 rearrangement in Drosophila has originally been recognized as a Shaker-like mutant because of its behavioral and electrophysiological phenotype. The gene whose expression is altered by the V7 rearrangement has been characterized. It encodes a novel Ca(2+)-binding protein named frequenin, which is related to recoverin and visinin. In vitro, the frequenin protein functions like recoverin as a Ca(2+)-sensitive guanylyl cyclase activator. Anti-frequenin antibodies stain the central and peripheral nervous system in Drosophila embryos and in larval and adult tissue sections. Frequenin appears to be particularly enriched in synapses, such as the motor nerve endings at neuromuscular junctions. Neuromuscular junctions of transgenic flies, which overexpress frequenin upon heat shock, exhibit an extraordinarily enhanced, frequency-dependent facilitation of neurotransmitter release, with properties identical to those observed in V7 junctions. We propose that frequenin represents a new element for the Ca(2+)-dependent modulation of synaptic efficacy.

Amino Acid Sequence↗
PubMed1992

Full sequence of neurocalcin, a novel calcium-binding protein abundant in central nervous system.

We determined the cDNA sequence for neurocalcin, a novel calcium-binding protein in bovine brain. This clone (pCalN) has 582 nucleotides in the open reading frame including the termination codon TGA, 11 nucleotides of the 5' leader and 1251 nucleotides of the 3' noncoding region. The deduced amino acid sequence revealed that neurocalcin is composed of 193 amino acids, has a molecular mass of 22,284 daltons, and contains three putative calcium-binding sites (EF-hand motifs). By Northern blot analysis, 3.8kbp mRNA was detected in brain. The deduced amino acid sequence had a strong homology to visinin (46.5%) and recoverin (51.6%) in retina, suggesting that neurocalcin may play a visinin- or recoverin-like role in brain.

Amino Acid Sequence↗
PubMed1992

Neurocalcin, a novel calcium binding protein with three EF-hand domains, expressed in retinal amacrine cells and ganglion cells.

Neurocalcin (molecular weight 23,000 and 24,000) is a newly identified Ca2+ binding protein with three EF-hand domains and has a strong amino acid sequence homology with visinin and recoverin (Terasawa, M., Nakano, A., Kobayashi, R., and Hidaka, H. J. Biol. Chem. In press). We produced antibody against neurocalcin. Immunoblotting showed the presence of neurocalcin in bovine retina as well as brain, suggesting that neurocalcin was a neuron specific Ca2+ binding protein. Immunohistochemistry revealed the expression of neurocalcin in retinal amacrine cells and ganglion cells but not in the photoreceptor layer. This distribution of neurocalcin was quite different from that of visinin and recoverin. Our results suggest that neurocalcin may play an important role in a Ca2+ signal pathway of the nervous system.

Animals↗
PubMed2000

Tubby-like protein 1 as an autoantigen in cancer-associated retinopathy.

Cancer-associated retinopathy (CAR) is a rare paraneoplastic syndrome that is characterized by retinal degeneration. Two cDNA clones, recoverin and tubby-like protein 1 (TULP1), were isolated from a human retinal cDNA library by using serum from a CAR patient as the probe. Both recoverin and TULP1 are retina-specific protein, and TULP1 is a member of tubby gene family. A determination of the recognized amino acid sequence of TULP1 by the patient serum and immunohistochemical studies on the distribution of TULP1 in the retina were done in this study.

Amino Acid Sequence↗
PubMed2000

Expression of the neuronal calcium sensor protein family in the rat brain.

The neuronal calcium sensor proteins are members of the calcium-binding protein superfamily. They control localized calcium signalling on membranes and may make G-protein cascades sensitive to cytosolic calcium. The family members are recoverin (visinin, S-modulin), neuronal calcium sensor-1 (frequenin), hippocalcin, neuronal visinin-like protein-1 (visinin-like protein, neurocalcin-alpha), neuronal visinin-like protein-2 and neuronal visinin-like protein-3. Recoverin is expressed only in the retina and pineal gland. Using in situ hybridization, we mapped the expression of the other neuronal calcium sensor protein genes in the adult rat brain. Neuronal visinin-like protein-1 messenger RNA has a widespread distribution and is abundant in all brain areas except the caudate-putamen. Neuronal calcium sensor-1 gene expression is pan-neuronal. Neuronal calcium sensor-1 messenger RNA is present in the dendrites of hippocampal pyramidal and granule cells, suggesting a specific role in dendritic function. Hippocalcin and neuronal visinin-like protein-2 are mainly expressed in the forebrain and have similar expression patterns (neocortex, hippocampus and caudate-putamen). Neuronal visinin-like protein-3 has the most restricted expression; its highest expression level is in the cerebellum (Purkinje and granule cells). However, the neuronal visinin-like protein-3 gene is also expressed in many ventral nuclei throughout the fore- and midbrain, in the medial habenulae, and in the superior and inferior colliculi. The neuronal calcium sensor proteins are a relatively unexplored family of Ca(2+)-binding proteins. They are likely to be involved in many diverse areas of neuronal signalling. In this paper, we describe their expression in the rat brain as determined by in situ hybridization. As all five neuronal calcium sensor protein genes have distinctive expression patterns, they probably perform specific functions.

Animals↗
PubMedDate not supplied

Glycine receptors in the rod pathway of the macaque monkey retina.

The distribution of glycinergic synapses in macaque monkey retina was investigated. The monoclonal antibody (mAb2b) against the alpha 1 subunit of the glycine receptor produced a punctate immunoreactivity that was localized to synapses. In central retina about 70% of the alpha 1 subunit-containing synapses were located in strata 1 and 2 of the inner plexiform layer, about 30% were located in strata 3 and 4, and immunoreactivity was absent in stratum 5. Electron microscopy showed that the majority of the synapses in strata 1 and 2 were on cone bipolar axons. The presynaptic profile always belonged to an amacrine cell. Presynaptic and postsynaptic profiles were further characterized using double-label immunofluorescence with cell-type specific antibodies against calcium-binding proteins. An antiserum against calretinin was used to label AII amacrine cells and an antiserum against recoverin was used to label flat midget bipolar cells. In the outer part of the IPL, 75% of the alpha 1-immunoreactive puncta were colocalized with calretinin-immunoreactive AII processes and 61% of the alpha 1-immunoreactive puncta were colocalized with recoverin-positive midget bipolar axons. These results suggest that the alpha 1 subunit of the glycine receptor is present at the chemical synapse made by AII amacrine cells with flat midget bipolar cells, thus providing a pathway for rod signals to reach midget ganglion cells.

Animals↗
PubMed2004

Lipid modulation of the activity of diacylglycerol kinase alpha- and zeta-isoforms: activation by phosphatidylethanolamine and cholesterol.

Diacylglycerol kinase (DGK) isoforms alpha and zeta were extracted from transfected cells that overexpressed these enzymes. We determined the lipid dependence of the binding of these isoforms to liposomes. The modulation by lipid of the rate of phosphorylation of diacylglycerol by these enzymes was also measured. Incorporation of phosphatidylethanolamine into the liposomes resulted in an increased partitioning of both isoforms of DGK to the membrane as well as an increased catalytic rate. We demonstrate that the increased catalytic rate is a consequence of both increased portioning of the enzyme to the membrane and increased catalytic activity of the membrane-bound form. DGKalpha, a calcium-dependent isoform, can be activated in a calcium-independent fashion in the presence of phosphatidylethanolamine. Similar effects are observed with cholesterol. In contrast, sphingomyelin inhibits the activity of both isoforms of DGK. Our results demonstrate that the translocation to membranes and activity of DGKalpha and DGKzeta are modulated by the composition and properties of the membrane. The enzymes are activated by the presence of lipids that promote the formation of inverted phases. However, the promotion of negative curvature is not the sole factor contributing to the lipid effects on enzyme binding and activity. A truncated form of DGKalphalacking both the E-F hand and the recoverin homology domain is constitutively active and is not further activated by any of the lipids tested or by calcium. However, a truncated form lacking only the recoverin homology domain is partially activated by either calcium or certain lipids.

Animals↗
PubMed2003

Neuronal calcium sensor-1: a multifunctional regulator of secretion.

Ca2+ ions play a crucial role not only as the trigger for neurotransmitter release, but also in other aspects of brain function, such as short-term and long-term modulation of synaptic efficacy, which may underlie certain forms of learning and memory. The actions of Ca2+ are mediated by Ca(2+)-binding proteins, including a group of proteins known as neuronal calcium sensor (NCS) proteins. The NCS family includes NCS-1, visinin-like proteins, recoverins, guanylate cyclase-activating proteins and potassium channel-interacting proteins. Some members of this family, such as recoverin and guanylate cyclase-activating protein, are only expressed in photoreceptor cells and have been implicated in the control of visual transduction pathways, while the functional roles of the other members are largely unknown. NCS-1 was originally identified in Drosophila in a screen for neuronal hyperexcitability mutants. NCS-1 is an N-terminally myristoylated protein that contains four EF-hand motifs, three of which are able to bind Ca2+ in the submicromolar range. Overexpression of NCS-1 has been shown to enhance evoked neurotransmitter release, paired-pulse facilitation and exocytosis in several neuronal and neuroendocrine cell types. Recent experiments suggest that NCS-1 interacts directly with phosphatidylinositol 4-hydroxykinase in yeast as well as mammalian cells, suggesting that it may enhance neuronal secretion by modulating cellular trafficking steps in a phosphoinositide-dependent manner. In contrast, an involvement of NCS-1 in the expression and regulation of voltage-gated Ca2+ channels and K+ channels has also been proposed, which may be attributed, at least in part, to the effects of NCS-1 on vesicular trafficking pathways. The present review describes current knowledge about the cellular functions and molecular mechanisms by which NCS-1 may regulate neurotransmitter release.

Animals↗
PubMed2000

A domain with homology to neuronal calcium sensors is required for calcium-dependent activation of diacylglycerol kinase alpha.

Diacylglycerol kinases (DGKs) phosphorylate diacylglycerol produced during stimulus-induced phosphoinositide turnover and attenuate protein kinase C activation. Diacylglycerol kinase alpha is an 82-kDa DGK isoform that is activated in vitro by Ca(2+). The DGK alpha regulatory region includes tandem C1 protein kinase C homology domains and Ca(2+)-binding EF hand motifs. It also contains an N-terminal recoverin homology (RVH) domain that is related to the N termini of the recoverin family of neuronal calcium sensors. To probe the structural basis of Ca(2+) regulation, we expressed a series of DGK alpha deletions spanning its regulatory domain in COS-1 cells. Deletion of the RVH domain resulted in loss of Ca(2+)-dependent activation. Further deletion of the EF hands resulted in a constitutively active enzyme, suggesting that sequences in or near the EF hands are sufficient for autoinhibition. Binding of Ca(2+) to the EF hands protected sites within both the RVH domain and EF hands from trypsin cleavage and increased the phenyl-Sepharose binding of a recombinant DGK alpha fragment that included both the RVH domain and EF hands. These observations suggested that Ca(2+) elicits a concerted conformational change of these two domains. A cationic amphiphile, octadecyltrimethylammonium chloride, also activated DGK alpha. As with Ca(2+), this activation required the RVH domain. However, this agent did not protect the EF hands and RVH domain from trypsin cleavage. These findings indicate that the EF hands and RVH domain act as a functional unit during Ca(2+)-induced DGK alpha activation.

Amino Acid Sequence↗
PubMed2000

Immunocytochemical localization and crystal structure of human frequenin (neuronal calcium sensor 1).

Frequenin, a member of a large family of myristoyl-switch calcium-binding proteins, functions as a calcium-ion sensor to modulate synaptic activity and secretion. We show that human frequenin colocalizes with ARF1 GTPase in COS-7 cells and occurs in similar cellular compartments as the phosphatidylinositol-4-OH kinase PI4Kbeta, the mammalian homolog of the yeast kinase PIK1. In addition, the crystal structure of unmyristoylated, calcium-bound human frequenin has been determined and refined to 1.9 A resolution. The overall fold of frequenin resembles those of neurocalcin and the photoreceptor, recoverin, of the same family, with two pairs of calcium-binding EF hands and three bound calcium ions. Despite the similarities, however, frequenin displays significant structural differences. A large conformational shift of the C-terminal region creates a wide hydrophobic crevice at the surface of frequenin. This crevice, which is unique to frequenin and distinct from the myristoyl-binding box of recoverin, may accommodate a yet unknown protein ligand.

Amino Acid Sequence↗