PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Colocalization”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 523 records · Page 29Linked to original sources

Characterization of the distribution of G alpha o in rat striatal synaptosomes and its colocalization with tyrosine hydroxylase.

Dopaminergic striatal synaptosomes can be detected and isolated with a fluorescence-activated cell sorter (FACS). In the present study, two antigens were detected simultaneously with primary antisera raised in different species and species-specific fluorescent secondary antibodies with different emission spectra. Double-label FACS analysis was used to determine whether tyrosine hydroxylase (TH) and the alpha subunit of Go (G alpha o) are colocalized in striatal synaptosomes. Rabbit antibodies generated against a synthetic fragment of G alpha o (corresponding to amino acids 22-35) combined with fluorescein-conjugated secondary antibodies were used to detect G alpha o-containing striatal synaptosomes. Preadsorption of G alpha o antiserum with the synthetic peptide antigen reduced labeling to the level obtained with preimmune serum. Approximately 65-75% of striatal synaptosomes were specifically labeled by G alpha o antiserum. Tyrosine hydroxylase-containing synaptosomes were detected with a mouse monoclonal antibody to TH and R-phycoerythrin-conjugated secondary antibody. They comprised 15-17% of total striatal synaptosomes. Double-label studies indicated that at least 50% of TH-containing synaptosomes also contained G alpha o. These findings suggest that G alpha o may not be a protein component of all striatal nerve terminals, and provide a basis for a role for G alpha o in signal transduction within subpopulations of intrinsic and afferent nerve terminals, including those of nigrostriatal dopamine neurons.

Animals↗

Cellular colocalization of dopamine D1 and D2 receptors in rat medial prefrontal cortex.

In a recent study in rat medial prefrontal cortex (mPFC), a fluorescently coupled, high-affinity ligand for the D1 receptor subtype was localized to nonpyramidal neurons, while a ligand selective for the D2 subtype was found on neurons with a size distribution overlapping with both small pyramidal and large nonpyramidal cells. These observations raised the possibility that a subpopulation of cortical neurons with an intermediate size range may coexpress both the D1 and D2 receptor subtypes. In the present study, the D1 and D2 receptor subtypes have been simultaneously localized in layer VI of rat mPFC using 20 nM SCH 23390-Bodipy and 20 nM N-(p-aminophenethyl) spiperone-Texas red, respectively, in the presence of 100 nM mianserin (5-HT2 receptor antagonist). The localization of receptor binding fluorescence was assessed in paired images using fluoroscein isothiocyanate (FITC) and rhodamine dichroic filters for the D1 and D2 subtypes, respectively. Under the conditions employed here, most cell bodies showed either D1-like or D2-like receptor binding fluorescence, while a colocalization of both fluoroprobes was observed on only 25% of the labeled cells. When the size of each single-labeled cell body was measured using the respective FITC (D1-probe) and rhodamine (D2-probe) epifluorescence filters, the distribution of cells showing only D1-like receptor binding fluorescence was similar to nonpyramidal neurons (68.6 +/- 1.8 microns 2), while that for cells showing only D2-like receptor binding fluorescence was similar to that of both large interneurons and small pyramidal cells (106.9 +/- 2.4 microns 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Biochemical characterization of mouse microsomal prostaglandin E synthase-1 and its colocalization with cyclooxygenase-2 in peritoneal macrophages.

We cloned the cDNA for mouse microsomal prostaglandin (PG) E synthase-1 (mPGES-1) and expressed the recombinant enzyme in Escherichia coli. The membrane fraction containing recombinant mPGES-1 catalyzed the isomerization of PGH2 to PGE2 in the presence of GSH with K(m) values of 130 microM for PGH2 and 37 microM for GSH, a turnover number of 600 min(-1), and a k(cat)/K(m) ratio of 4.6 min(-1) microM(-1). Recombinant mPGES-1 was purified and used to generate a polyclonal antibody highly specific for mPGES-1. The antibody showed a single band on Western blotting of microsomal fractions from lipopolysaccharide-treated mouse peritoneal macrophages. Northern and Western blotting analyses revealed that mPGES-1 was induced together with cyclooxygenase-2 in mouse macrophages after treatment of the cells with lipopolysaccharide. Confocal immunofluorescence microscopy revealed that both mPGES-1 and cyclooxygenase-2 were colocalized in the lipopolysaccharide-treated macrophages. Taken together, these results demonstrate that mPGES-1 is an efficient downstream enzyme for the production of PGE2 in the activated macrophages treated by lipopolysaccharide.

Animals↗

The tumor suppressor protein APC colocalizes with beta-catenin in the colon epithelial cells.

The APC gene is mutated in familial adenomatous polyposis and sporadic colorectal tumors. The product of this gene is a 300 kDa cytoplasmic protein associated with catenin. In the present study, we examined the subcellular localization of the APC protein and beta-catenin in the mouse colon by double-labeling immunocytochemistry. While the APC protein was localized in the lateral and apical cytoplasm and in microvilli of the epithelial cells, beta-catenin was present exclusively in the lateral cytoplasm. Double-labeling-immunoelectron microscopy demonstrated precise colocalization of the APC protein and beta-catenin along the lateral plasma membrane. These results suggest that the APC protein functions in cooperation with beta-catenin in the lateral cytoplasm but has other functions independent of beta-catenin in the apical cytoplasm and in microvilli.

Adenomatous Polyposis Coli Protein↗

70-kDa heat-shock cognate protein colocalizes with karyophilic proteins into the nucleus during their transport in vitro.

Recently, we showed that antibodies against 70-kDa heat-shock cognate 66otein (hsc70) inhibit nuclear transport of karyophilic proteins in vivo. In this study, we examined the involvement of hsc70 in nuclear transport using a digitonin-permeabilized cell-free transport system. Depletion of the cytosolic extract required for nuclear transport of hsc70 by incubation with anti-hsc70 antibodies reduced the nuclear transport activity significantly, and addition of purified hsc70 to the depleted extract restored the transport activity. We examined the localization of hsc70 during nuclear transport in vitro by indirect immunofluorescence studies. Hsc70 accumulated in the nucleus when bovine serum albumin (BSA) conjugated to SV40 large T-antigen nuclear localization signal (NLS) peptides (T-BSA) or nucleoplasmin was added exogenously to the cytosolic extract, but not when BSA conjugated to transport-incompetent point-mutated NLS peptide was added. This karyophilic protein-dependent accumulation of hsc70 was dependent on the cytosolic extract, temperature, and ATP and was sensitive to wheat germ agglutinin. Addition of excess unlabeled T-BSA to the cytosolic extract competitively inhibited the nuclear accumulation of fluorescently labeled T-BSA or nucleoplasmin, but did not affect accumulation of hsc70 into the nucleus. These results show that hsc70 is required for nuclear transport and that it is colocalized with karyophilic proteins during their active import into the nucleus in vitro.

Adenosine Triphosphate↗

Colocalization of nestin and vimentin/desmin in skeletal muscle cells demonstrated by three-dimensional fluorescence digital imaging microscopy.

During skeletal muscle development three intermediate filament proteins are expressed: nestin, vimentin, and desmin. Vimentin and desmin belong to the class III intermediate filaments and are closely related to each other, whereas nestin is a more distantly related, class VI, intermediate filament. It was previously observed by conventional immunocytochemistry that the intracellular patterns of nestin, desmin, and vimentin appeared indistinguishable, despite nestin's more distant evolutionary relationship. We here extend this analysis by applying three-dimensional fluorescence digital imaging microscopy to compare the intracellular distribution of nestin with that of desmin, vimentin, actin, and tubulin in G6 human fetal skeletal muscle cells. We show that in vitro differentiation of G6 cells can produce an intermediate filament expression pattern similar to that observed during myogenesis in vivo, i.e., downregulation of vimentin but not of nestin and desmin during myotube maturation. The image analysis demonstrated that the degree of overlap between nestin and desmin/vimentin was very extensive in myoblasts and in multinucleate myotubes in all regions of the cells. In contrast, nestin did not colocalize with tubulin or actin in G6 myoblasts. In particular, nestin immunoreactivity was not detected at the microtubule-organizing center, and it was only sparsely observed at the cell periphery where actin stress fibers were seen. Our data lend further support to the notion that nestin interacts very closely with the two more distantly related class III intermediate filament proteins desmin and vimentin in the entire muscle cell, before and after myotube formation. A comparison of conserved amino acid residues in the different IFs suggest that charged amino acid residues in the alpha-helical rod domain may play a role in the interaction.

Amino Acid Sequence↗

Components of the nucleolar processing complex (Pre-rRNA, fibrillarin, and nucleolin) colocalize during mitosis and are incorporated to daughter cell nucleoli.

We have traced in onion root cells the mitotic course of rRNA, of the RNA synthesized in the G2 period of the preceding interphase, and of the nucleolar proteins fibrillarin and nucleolin. The rRNA was detected by ultrastructural in situ hybridization with a rDNA probe capable of hybridizing mature rRNAs and also the intermediate forms of pre-rRNA processing. The RNA synthesized in the preceding G2 (which, according to classical data, is mostly rRNA) was revealed by autoradiography on synchronous cells labeled in G2 by tritiated uridine. Fibrillarin was detected by immunofluorescence in both mammalian and onion cells; the results in the latter cells were compared with those obtained after AgNOR staining. Electron microscopical immunocytochemistry was used to detect fibrillarin and nucleolin in onion cells. In all cases, following nucleolar dispersion in prophase, the signal was detected in the chromosome periphery during metaphase and anaphase, in irregular fibrillar masses located between chromosomes in ana-telophase, in prenucleolar bodies during telophase, and in the newly formed nucleoli, after nucleologenesis. Moreover, as expected, ribosomes appeared labeled after in situ hybridization, but a dispersed cytoplasmic labeling was observed in all experiments, mainly during metaphase and anaphase. These results demonstrate that nucleolar components involved in pre-rRNA processing, including rRNA itself, probably in an incompletely processed form, are transferred from the parental to the daughter cell nucleoli by means of transient structures, such as the perichromosomal sheath and prenucleolar bodies. Since these macromolecular components are assembled in the interphase nucleolus, forming the RNP processing complex, their colocalization during mitosis in the same transient structures strongly suggests that at least a subset of these complexes does not disaggregate during cell division, but remains assembled and becomes incorporated to the new nucleolus. Therefore, ribosome biogenesis restarts not only after mitosis at the level of transcription, but also at the intermediate levels of pre-rRNA processing.

Allium↗

Neurofibromin colocalizes with mitochondria in cultured cells.

Mutations in neurofibromatosis type 1 target the gene coding for neurofibromin. While neurofibromin is able to accelerate the rate of GTP hydrolysis by cellular Ras proteins, its biological function is not well understood. To gain information regarding its function, the intracellular localization of neurofibromin was analyzed in cultured cell lines using polyclonal antisera raised against four neurofibromin-specific peptides, three from the carboxyl terminus and one from the amino terminus. In methanol-fixed cells distinct rod-like structures distributed throughout the cytoplasm were recognized by the antisera. Similar structures were seen with each antiserum, including affinity-purified antibodies, and in each of the cultured cell lines tested. Similar structures were seen in paraformaldehyde-fixed cells. Double staining experiments showed that these structures colocalize with mitochondria, but not with actin, beta-tubulin, or endoplasmic reticulum. When actin or tubulin structures within the cell were disrupted by separate antimitotic drugs, these stained structures retained their shape. Neurofibromin association with mitochondria was confirmed biochemically when highly purified mitochondrial fractions from bovine heart tissue were shown in Western analysis to contain neurofibromin. This association might be helpful in predicting identification of some of the cellular proteins with which neurofibromin interacts.

3T3 Cells↗

A p85 subunit-independent p110alpha PI 3-kinase colocalizes with p70 S6 kinase on actin stress fibers and regulates thrombin-stimulated stress fiber formation in swiss 3T3 cells.

The signaling pathways linking receptor activation to actin stress fiber rearrangements during growth factor-induced cell shape change are still to be determined. Recently our laboratory demonstrated the involvement of p70 S6 kinase (p70(s6k)) activation in thrombin-induced stress fiber formation in Swiss 3T3 cells. The present work shows that thrombin-induced p70(s6k) activation is inhibited by the PI 3-kinase inhibitors wortmannin and LY-294002. These inhibitors also significantly reduced thrombin-induced stress fiber formation, demonstrating a role for PI 3-kinase activity in this process, most likely upstream of p70(s6k). Furthermore, the p110alpha form of PI 3-kinase was localized to actin stress fibers, as was previously shown for p70(s6k), as well as to a golgi-like distribution. In contrast, PI 3-kinase p110gamma colocalized with microtubules. The PI 3-kinase p85 subunit, known to be capable of association with p110alpha, was present in a predominantly golgi-like distribution with no presence on actin filaments, suggesting the existence of distinctly localized PI 3-kinase pools. Immunodepletion of p85 from cell lysates resulted in only partial depletion of p110alpha and p110alpha-associated PI 3-kinase activity, confirming the presence of a p85-free p110alpha pool located on the actin stress fibers. Our data, therefore, point to the importance of subcellular localization of PI 3-kinase in signal transduction and to a novel action of p85 subunit-independent PI 3-kinase p110alpha in the stimulation by thrombin of p70(s6k) activation and actin stress fiber formation.

3T3 Cells↗

The nuclear DEAD box RNA helicase p68 interacts with the nucleolar protein fibrillarin and colocalizes specifically in nascent nucleoli during telophase.

The DEAD box protein, p68, is an established RNA-dependent ATPase and RNA helicase in vitro, but neither the physiological function of this protein nor the macromolecules with which it interacts are known. Using a yeast two-hybrid screen, we identified the nucleolar protein, fibrillarin, as a protein that interacts with p68. Coimmunoprecipitation experiments confirmed that p68 and fibrillarin can form complexes in cellular extracts, and deletion analysis identified regions in each protein responsible for mediating the interaction. Immunofluorescence studies using confocal microscopy revealed that, in interphase cells, while fibrillarin is predominantly nucleolar, p68 shows a diffuse granular nuclear staining but is largely excluded from the nucleoli. Strikingly, both proteins colocalize in nascent nucleoli during late telophase. These data are consistent with a role for p68 either in postmitotic nucleolar reassembly or in the activation of ribosomal DNA transcription/preribosomal RNA processing during telophase and suggest that differential subnuclear compartmentalization may be a mechanism by which interaction of p68 with fibrillarin is regulated in the cell.

Adenosine Triphosphatases↗

Synaptic distribution of the AMPA-GluR2 subunit and its colocalization with calcium-binding proteins in rat cerebral cortex: an immunohistochemical study using a GluR2-specific monoclonal antibody.

Due to its role as the dominant AMPA receptor subunit in respect to regulation of calcium permeability, information on the neuronal localization of GluR2 is of particular importance, yet has been hampered by the lack of a GluR2-specific antibody. Monoclonal antibodies were raised against the putative N-terminal portion (amino acids 175--430) of GluR2, using the fusion protein linked to trpE as an antigen. Western blot analysis and immunocytochemistry of transiently transfected human embryonic kidney 293 cells unambiguously confirmed the specificity of monoclonal antibody 6C4 for GluR2, which did not recognize or cross-react with any other AMPA/Kainate GluR subunits expressed. 6C4 was used in immunohistochemical studies to characterize the regional, cellular, and subcellular distribution of the GluR2 subunit at the light and electron microscopic levels in rat hippocampus and somatosensory cortex and in colocalization studies with the three calcium-binding proteins: parvalbumin, calbindin, and calretinin. GluR2 was widely distributed in both pyramidal cells and interneurons. Asymmetric synapses were labeled on both spines and small dendritic shafts. In contrast to previous reports, our double labeling studies using monoclonal antibody 6C4 with polyclonal antisera against calcium-binding proteins demonstrated that 84--97% of parvalbumin and calbindin-immunoreactive and 45--66% of the calretinin-immunoreactive interneurons in CA1 and somatosensory cortex also contain GluR2. These data have important implications regarding heterogeneity in calcium permeability of AMPA receptors across cell types in neocortex and hippocampus, as well as for differential vulnerability to excitotoxic injury.

Animals↗

Electron microscopy of colocalization of GABA and tyrosine hydroxylase expression in rat olfactory bulb transplants.

Juxtaglomerular (JG) neurons of rat olfactory bulb (OB) are a subset of inhibitory interneurons within the OB, acting via lateral inhibition to modulate the afferent input of the primary olfactory nerve. The JG neurons, composed of periglomerular, external tufted, and short axon cells, have been found to express various neurotransmitters, including gamma-amino butyric acid (GABA) and dopamine. A specific set of neurons within the periglomerular population have also been shown to coexpress these neurotransmitters. Deafferentation or functional odor deprivation of the normal OB causes a loss of tyrosine hydroxylase (TH) (the rate limiting enzyme in the dopamine synthesis pathway) expression within the JG cell population, but appears to have no effect on GABA levels. Our laboratory has developed a transplantation model to further study the effects of deafferentation and subsequent reinnervation within this system. Sections from transplant (TX) OBs were reacted for GABA and TH using immunocytochemical localization protocols and studied by electron microscopy. Numerous neuronal populations were found to be either TH or GABA positive in this study, with a specific subpopulation showing colocalization of both. Although the architecture of the TX OB is somewhat disrupted and the TH- and GABA-positive cells were not as uniform in their arrangement as they are in the normal OB, we found that these cells in the TX OB were morphologically similar to the JG cells of normal OB. Positively labeled profiles were also found to receive and form numerous synaptic contacts with both host olfactory nerve axons as well as with the processes of donor neurons. These synaptic contacts were within areas that resemble the glomeruli of normal OB, suggesting that lateral inhibition may occur within the TX OB as it does in the normal. The coexpression of GABA and TH within specific neurons also indicates that a unique population of JG neurons that occur in normal OB are also found within this transplanted system as well.

Animals↗

Possible gonadotropin cells in the lamprey pituitary: colocalization of mammalian LH-like immunoreactivity and glycoconjugate in adult sea lampreys (Petromyzon marinus).

In lampreys, although gonadotropin (GTH) has not yet been isolated from the pituitary gland, the presence of GTH has been strongly suggested. To detect possible GTH in the sea lamprey (Petromyzon marinus) pituitary, two different cytochemical probes were tested: One was the use of antibodies to GTHs, and the other was the use of lectin-screening kits for demonstration of glycoconjugate in hormonal molecules. GTH-like immunoreactivity was found in cells distributed in the ventral half of the proximal pars distalis. These cells were stained intensely by all four lots of anti-ovine LH including LHbeta, and were stained moderately or weakly by several other antibodies to LH-related GTHs, such as human LHbeta, hCGbeta, amphibian LH, and sturgeon GTH IIbeta. On the other hand, there were no positive reactions in the sea lamprey pituitary using the antibodies to FSH-related GTHs, thyrotropin (TSH), or pituitary glycoprotein hormones of teleost origin. Thus, GTH-like material in the sea lamprey pituitary seems to be more closely related to mammalian-like LH, rather than to FSH or TSH, as far as immunocytochemical determinants. A total of 21 kinds of lectins was tested. Among those, GTH-positive cells were also stained positively by concanavalin A and Vicia villosa agglutinin. Thus, the present study demonstrates colocalization of LH-like immunoreactivity and glycoconjugate in cells in the ventral half of the proximal pars distalis of the sea lamprey pituitary. It is suggested that those cells are most likely to be GTH cells in the sea lamprey pituitary.

Animals↗

Colocalization of GnRH binding sites with gonadotropin-, somatotropin-, somatolactin-, and prolactin-expressing pituitary cells of the pejerrey, Odontesthes bonariensis, in vitro.

Previous studies in the pejerrey, Odontesthes bonariensis, have demonstrated that fibers with immunoreactivity to gonadotropin-releasing hormone (ir-GnRH) reach all areas of the pituitary gland, the rostral pars distalis (RPD), the proximal pars distalis (PPD), and the pars intemedia (PI). A close association was shown between ir-GnRH fibers and gonadotropin (GtH)-, growth hormone (GH)-, somatolactin (SL)-, and prolactin (PRL)-expressing cells. The presence of only one GnRH variant, suspected to be a novel form, has been shown in pituitary extracts of this fish. In addition, GnRH may stimulate GtHs, GH, SL, and PRL levels in different fish species. The objective of the present study was to seek GnRH receptors and therefore colocalization with GtHs, GH, SL, and PRL cells in O. bonariensis using a pituitary primary cell culture system. GnRH binding sites were revealed by autoradiography of an iodinated superactive GnRH agonist ([(125)I]GnRH-A) and pituitary cells were identified by immunocytochemistry using piscine antisera. Following autoradiography, silver grains representing specific [(125)I]GnRH-A binding were associated with anti GtH, GH, SL, and PRL positive cells. These results demonstrate the presence of GnRH binding sites on these cells. It is suggested that GnRH may play a wide role in the neuroendocrine control of different pituitary hormones in addition to the GtHs.

Animals↗

Three members of the nitric oxide synthase II gene family (NOS2A, NOS2B, and NOS2C) colocalize to human chromosome 17.

Nitric oxide synthases (NOSs) are a family of enzymes responsible for the synthesis of nitric oxide from L-arginine and molecular oxygen. Three human NOS enzymes (I, II, and III) with differing cellular distribution and regulatory mechanisms have been identified. To determine whether additional NOSs are encoded in the human genome, a bovine NOS II-related cDNA was used to screen two human genomic libraries. Clones containing three independent genes were isolated. One clone encoded the previously identified NOS II gene (NOS2A). The two other genes specified amino acids homologous, but not identical, to human NOS II (NOS2B and NOS2C). Southern blot hybridization demonstrated that all three genes are present in the human genome. DNA from human-mouse somatic cell hybrids were used to determine the chromosomal location of the NOS II-related genes. All three NOS II-related genes colocalized to human chromosome 17 between bands p13.1 and q25. These observations suggest that there is more than one NOS II-related gene in the human genome. This finding may have important implications for the design of NOS isoform-specific inhibitors.

Amino Acid Sequence↗

WAC, a novel WW domain-containing adapter with a coiled-coil region, is colocalized with splicing factor SC35.

WW domains mediate protein-protein interactions in many intracellular processes. In pre-mRNA splicing, WW domains participate in cross-intron bridging. These WW domains are characterized by a central aromatic block of three tyrosine residues. We identified a novel protein containing the same type of WW domain. The gene encoding the protein, named WAC, is located in human chromosome 10p11.2-10p12.1. A Drosophila melanogaster WAC homolog (CG8949) was identified as a Rosetta stone protein. Domain fusion analysis of the Rosetta stone protein linked WAC to splicing factor SNRP70. WAC existed mainly in a tyrosine-phosphorylated form. Immunofluorescence analysis colocalized WAC with SC35, the marker for pre-mRNA splicing machinery. Our analysis suggests that WAC represents a novel member of WW-domain-containing proteins for RNA processing.

Amino Acid Sequence↗

Fos induced by mating or noncontact sociosexual interaction is colocalized with androgen receptors in neurons within the forebrain, midbrain, and lumbosacral spinal cord of male rats.

This study was designed to determine the extent to which Fos immunoreactivity (induced either by mating or noncontact sociosexual interaction) and androgen receptor (AR) immunoreactivity are colocalized in brain and spinal cord of male rats. Some males (Mated) were allowed to mate to ejaculation; others (Social Controls) were placed with females but physical contact was prevented by a wire mesh screen; remaining males (Isolated) were placed alone in the test jar for the duration of the test period. After testing, brains and spinal cords were examined for AR and Fos immunoreactivity (ir). PG21 anti-AR and anti-c-fos primary antibodies were visualized by fluorescence microscopy using cyanine-conjugated and fluorescein-conjugated secondary antibodies. In both brain and spinal cord, the number of Fos-ir neurons varied according to group: Mated males > Social Controls > Isolated males. Fos was highly localized in subsets of AR-ir neurons within the medial preoptic nucleus, bed nucleus of the stria terminalis, dorsomedial nucleus of the amygdala, and central tegmental field. Fos was also localized in subsets of AR-ir neurons within the L5, L6, and S1 segments of the spinal cord. Spinal cord concentrations of AR-ir and Fos-ir neurons were greatest in Lamina X, and the vast majority of Fos-ir neurons in the dorsal part of Lamina X were also AR-ir. Thus, in both brain and spinal cord, androgen-sensitive neurons are active during mating, and transmission of sexually relevant information from cord to brain is probably accomplished via hormone-sensitive spinal neurons.

Animals↗

Bral1, a brain-specific link protein, colocalizing with the versican V2 isoform at the nodes of Ranvier in developing and adult mouse central nervous systems.

Bral1, a brain-specific hyaluronan-binding protein, has been cloned recently. To gain insight into the role of Bral1, we generated a specific antibody against this protein. We have examined the detailed localization pattern of Bral1 protein and compared it with that of other members of the lectican proteoglycan family, such as brevican and versican, with which Bral1 is predicted to interact. The immunoreactivity of Bral1 antibody was predominantly observed in myelinated fiber tracts in the adult brain and could be detected at P20 in the white matter of the developing cerebellum, suggesting that expression starts when axonal myelination takes place. Furthermore, immunostaining demonstrated that Bral1 colocalized with the versican V2 isoform at the nodes of Ranvier. The present data suggest that Bral1 may play a pivotal role in the formation of the hyaluronan-associated matrix in the CNS that facilitates neuronal conduction by forming an ion diffusion barrier at the nodes.

Amino Acid Sequence↗