Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 67-kD elastin-binding protein (EBP) mediates cell adhesion to elastin and elastin fiber assembly, and it is similar, if not identical, to the 67-kD enzymatically inactive, alternatively spliced beta-galactosidase. The latter contains an elastin binding domain (S-GAL) homologous both to the aorta EBP and to NH2-terminal sequences of serine proteinases (Hinek, A., M. Rabinovitch, F. W. Keeley, and J. Callahan. 1993. J. Clin. Invest. 91:1198-1205). We now confirm the functional importance of this homology by showing that elastolytic activity of a representative serine elastase, porcine pancreatic elastase, was prevented by an antibody (anti-S-GAL) and by competing with purified EBP or S-GAL peptide. Immunohistochemistry of adult aorta indicates that the EBP exists as a permanent component of mature elastic fibers. This observation, together with the in vitro studies, suggests that the EBP could protect insoluble elastin from extracellular proteolysis and contribute to the extraordinary stability of this protein. Double immunolabeling of fetal lamb aorta with anti-S-GAL and antitropoelastin antibodies demonstrated, under light and electron microscopy, intracellular colocalization of the proteins in smooth muscle cells (SMC). Incubation of SMC with galactosugars to dissociate tropoelastin from EBP caused intracellular aggregation of tropoelastin. A tropoelastin/EBP complex was extracted from SMC lysates by coimmunoprecipitation and cross-linking, and its functional significance was addressed by showing that its dissociation by galactosugars caused degradation of tropoelastin by endogenous serine proteinase(s). This suggests that the EBP may also serve as a "companion" to intracellular tropoelastin, protecting this highly hydrophobic protein from self-aggregation and proteolytic degradation.
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PMID:67-kD elastin-binding protein is a protective "companion" of extracellular insoluble elastin and intracellular tropoelastin. 803 52

We and others have previously shown that a 67-kD cell surface elastin/laminin-binding protein (EBP) is responsible for cell adhesion to elastin and laminin and for mediating the process of elastin fiber assembly, but the nature of this protein was unknown. In this report we provide evidence that a 67-kD catalytically inactive form of beta-galactosidase produced by alternative splicing demonstrates immunological and functional similarity and sequence homology to the 67-kD EBP, suggesting that the two might be the same. Antibody prepared to a synthetic peptide, N-Ac-GSPSAQDEASPL, corresponding to a frame-shift-generated sequence unique to the alternatively spliced form of human beta-galactosidase, also recognized sheep EBP both on Western blotting and in aortic tissue. Furthermore, this synthetic peptide (S-GAL) binds to elastin and laminin, but not to fibronectin, collagen I, or collagen III. Moreover, both tropoelastin and laminin which bind to S-GAL peptide affinity columns can be specifically eluted from them with an excess of free S-GAL peptides. In addition, sequence homology among this splice variant of human beta-galactosidase, sheep EBP, and NH2-terminal sequences of some elastases suggests that these proteins share a common ligand-binding motif that has not been previously recognized.
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PMID:The 67-kD elastin/laminin-binding protein is related to an enzymatically inactive, alternatively spliced form of beta-galactosidase. 838 99

Numerous cell types express the 67 kDa galactolectin related to the alternatively spliced variant of beta-galactosidase. This 67 kDa protein, while present on cell surfaces, mediates cell contacts with elastin, laminin and collagen type IV. In elastin-producing tissues, the 67 kDa protein also co-localizes with intracellular tropoelastin and mature elastic fibres. We have established that this elastin binding protein (EBP) serves as a molecular chaperone for tropoelastin. The EBP binds this highly hydrophobic and unglycosylated ligand intracellularly, protecting it from intracellular self aggregation and premature proteolytic degradation, and mediates its orderly assembly upon the microfibrillar scaffold. While some of this protein is incorporated as a permanent component of elastic fibres, most of the EBP, after extracellular dissociation from its ligand, recycles back to the intracellular endosomal compartment and re-associates with the newly synthesized tropoelastin. We suggest that recycling of this reusable shuttle protein is imperative for the effective extracellular deposition of insoluble elastin.
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PMID:The 67 kDa spliced variant of beta-galactosidase serves as a reusable protective chaperone for tropoelastin. 857 57

The 67-kDa protein identical to the enzymatically inactive spliced variant of beta-galactosidase is a major component of the non-integrin cell surface receptor expressed on fibroblasts, smooth muscle cells, chondroblasts, leukocytes, and certain cancer cell types. It recognizes several non-identical hydrophobic domains on elastin, laminin, and type IV collagen, provided they form a similar secondary conformation. The 67-kDa protein is not a transmembrane molecule, but immobilizes on the cell surface by an association with two other proteins, the 61-kDa neuraminidase and the 55-kDa 'protective protein'. The 67-kDa protein binds to matrix ligands in a calcium independent manner and only in the absence of galactosugars. Binding of these carbohydrate-bearing moieties causes such conformational changes of the 67-kDa protein that it loses the ability to bind its principal matrix ligands and separates from the cell surface. Galactosugars which inactivate this unique cell surface receptor may therefore modulate cell-matrix interactions, especially in such processes as SMC migration during vascular thickening, tumor cell metastasis, or tissue infiltration by the leukocytes. In elastin-producing cells, the 67-kDa protein associates with tropoelastin and serves as a molecular chaperone which facilitates its intracellular transport and extracellular assembly.
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PMID:Biological roles of the non-integrin elastin/laminin receptor. 892 81

We have previously shown that intracellular trafficking and extracellular assembly of tropoelastin into elastic fibers is facilitated by the 67-kD elastin-binding protein identical to an enzymatically inactive, alternatively spliced variant of beta-galactosidase (S-Gal). In the present study, we investigated elastic-fiber assembly in cultures of dermal fibroblasts from patients with either Morquio B disease or GM1-gangliosidosis who bore different mutations of the beta-galactosidase gene. We found that fibroblasts taken from patients with an adult form of GM1-gangliosidosis and from patients with an infantile form, carrying a missense mutations in the beta-galactosidase gene-mutations that caused deficiency in lysosomal beta-galactosidase but not in S-Gal-assembled normal elastic fibers. In contrast, fibroblasts from two cases of infantile GM1-gangliosidosis that bear nonsense mutations of the beta-galactosidase gene, as well as fibroblasts from four patients with Morquio B who had mutations causing deficiency in both forms of beta-galactosidase, did not assemble elastic fibers. We also demonstrated that S-Gal-deficient fibroblasts from patients with either GM1-gangliosidosis or Morquio B can acquire the S-Gal protein, produced by coculturing of Chinese hamster ovary cells permanently transected with S-Gal cDNA, resulting in improved deposition of elastic fibers. The present study provides a novel and natural model validating functional roles of S-Gal in elastogenesis and elucidates an association between impaired elastogenesis and the development of connective-tissue disorders in patients with Morquio B disease and in patients with an infantile form of GM1-gangliosidosis.
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PMID:Impaired elastic-fiber assembly by fibroblasts from patients with either Morquio B disease or infantile GM1-gangliosidosis is linked to deficiency in the 67-kD spliced variant of beta-galactosidase. 1084 12

The elastin-binding proteins EbpS of Staphylococcus aureus strains Cowan and 8325-4 were predicted from sequence analysis to comprise 486 residues. Specific antibodies were raised against an N-terminal domain (residues 1-267) and a C-terminal domain (residues 343-486) expressed as recombinant proteins in Escherichia coli. Western blotting of lysates of wild-type 8325-4 and Newman and the corresponding ebpS mutants showed that EbpS migrated with an apparent molecular mass of 83 kDa. The protein was found exclusively in cytoplasmic membrane fractions purified from protoplasts or lysed cells, in contrast to the clumping factor ClfA, which was cell-wall-associated. EbpS was predicted to have three hydrophobic domains H1-(205-224), H2-(265-280), and H3-(315-342). A series of hybrid proteins was formed between EbpS at the N terminus and either alkaline phosphatase or beta-galactosidase at the C terminus (EbpS-PhoA, EbpS-LacZ). PhoA and LacZ were fused to EbpS between hydrophobic domains H1-H2 and H2-H3, and distal to H3. Expression of enzymatic activity in E. coli showed that EbpS is an integral membrane protein with two membrane-spanning domains H1 and H3. N-terminal residues 1-205 and C-terminal residues 343-486 were predicted to be exposed on the outer face of the cytoplasmic membrane. The ligand-binding domain of EbpS is known from previous studies to be present in the N terminus between residues 14-34 and probing whole cells with anti-EbpS1-267 antibodies indicated that this region is exposed on the surface of intact cells. This was also confirmed by the observation that wild-type S. aureus Newman cells bound labeled tropoelastin whereas the ebpS mutant bound 72% less. In contrast, the C terminus, which carries a putative LysM peptidoglycan-binding domain, is not exposed on the surface of intact cells and presumably remains buried within the peptidoglycan. Finally, expression of EbpS was correlated with the ability of cells to grow to a higher density in liquid culture, suggesting that EbpS may have a role in regulating cell growth.
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PMID:The elastin-binding protein of Staphylococcus aureus (EbpS) is expressed at the cell surface as an integral membrane protein and not as a cell wall-associated protein. 1168 86

We have established previously that the 67-kDa elastin-binding protein (EBP), identical to the spliced variant of beta-galactosidase, acts as a recyclable chaperone that facilitates secretion of tropoelastin. (Hinek, A., Keeley, F. W., and Callahan, J. W. (1995) Exp. Cell Res. 220, 312-324). We now demonstrate that EBP also forms a cell surface-targeted molecular complex with protective protein/cathepsin A and sialidase (neuraminidase-1), and provide evidence that this sialidase activity is a prerequisite for the subsequent release of tropoelastin. We found that treatment with sialidase inhibitors repressed assembly of elastic fibers in cultures of human skin fibroblasts, aortic smooth muscle cells, and ear cartilage chondrocytes and caused impaired elastogenesis in developing chick embryos. Fibroblasts derived from patients with congenital sialidosis (primary deficiency of neuraminidase-1) and galactosialidosis (secondary deficiency of neuraminidase-1) demonstrated impaired elastogenesis, which could be reversed after their transduction with neuraminidase-1 cDNA or after treatment with bacterial sialidase, which has a similar substrate specificity to human neuraminidase-1. We postulate that neuraminidase-1 catalyzes removal of the terminal sialic acids from carbohydrate chains of microfibrillar glycoproteins and other adjacent matrix glycoconjugates, unmasking their penultimate galactosugars. In turn, the exposed galactosugars interact with the galectin domain of EBP, thereby inducing the release of transported tropoelastin molecules and facilitating their subsequent assembly into elastic fibers.
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PMID:Lysosomal sialidase (neuraminidase-1) is targeted to the cell surface in a multiprotein complex that facilitates elastic fiber assembly. 1631 20

G(M1)-gangliosidosis is a lysosomal storage disorder caused by acid beta-galactosidase deficiency. Aside from the lysosomal beta-galactosidase enzyme, the beta-galactosidase gene also encodes the elastin-binding protein (EBP), deficiency in which impairs elastogenesis. Using expression studies and Western blots of COS-1 cells, we identified and characterized four new and two known beta-galactosidase gene mutations detected in G(M1)-gangliosidosis patients with infantile, juvenile, or adult forms of disease. We then focused on impaired elastogenesis detected in fibroblasts from patients with infantile and juvenile disease. The juvenile patient showed connective-tissue abnormalities, unusual urinary keratan sulfate excretion, and an EBP reduction, despite mutations affecting only beta-galactosidase. Because galactosugar-bearing moieties may alter EBP function and impair elastogenesis, we assessed infantile and juvenile patients for the source of altered elastogenesis. We confirmed that the infantile patient's impaired elastogenesis arose from a primary EBP defect, according to molecular analysis. We examined the juvenile's fibroblasts by immunohistochemistry, addition of keratanase, soluble/insoluble elastin assay, and radiolabeling of tropoelastin. These experiments revealed that the juvenile's impaired elastogenesis likely arose from secondary EBP deficiency caused by keratan sulfate accumulation. Thus, impaired elastogenesis in G(M1)-gangliosidosis can arise from primary or secondary EBP defects in fibroblasts from infantile and juvenile patients, respectively.
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PMID:Primary and secondary elastin-binding protein defect leads to impaired elastogenesis in fibroblasts from GM1-gangliosidosis patients. 1631 80

The human GLB1 gene encodes a lysosomal beta-galactosidase (beta-Gal) and an elastin-binding protein (EBP). Defect of the EBP as a chaperon for tropoelastin and a component of receptor complex among neuraminidase-1 (NEU1) and protective protein/cathepsin A (PPCA) is suggested responsible for impaired elastogenesis in autosomal recessive beta-Gal, PPCA and NEU1 deficiencies. The purpose of this study is to determine effects of GLB1, PPCA and NEU1 gene mutations on elastogenesis in skin fibroblasts. Elastic fiber formation and the EBP mRNA expression were examined by immunofluorescence with an anti-tropoelastin antibody and RT-PCR selective for EBP in skin fibroblasts with these lysosomal enzyme deficiencies. Apparently normal elastogenesis and EBP mRNA expression were observed for fibroblasts from Morquio B disease cases with the GLB1 gene alleles (W273L/W273L, W273L/R482H and W273L/W509C substitutions, respectively), a galactosialidosis case with the PPCA allele (IVS7+3A/IVS7+3A) and a sialidosis case with the NEU1 allele (V217M/G243R) as well as normal subject. In this study, the W273L substitution in the EBP could impossibly cause the proposed defect of elastogenesis, and the typical PPCA splicing mutation and the V217M/G243R substitutions in the NEU1 might hardly have effects on elastic fiber formation in the dermal fibroblasts.
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PMID:Elastogenesis in cultured dermal fibroblasts from patients with lysosomal beta-galactosidase, protective protein/cathepsin A and neuraminidase-1 deficiencies. 1653 2

Impaired elastic fiber assembly constitutes one major problem in skin wound healing. Recent data indicate that a ternary complex involving a splicing form of beta-galactosidase associated with cathepsin-A and neuraminidase-1 directs the transport of tropoelastin to the fibroblast plasma membrane and participates in the deposition of the elastin precursor onto a microfibrillar scaffold. In addition, this elastin receptor complex is ubiquitously expressed and also acts as a true receptor for elastin-derived peptides produced during the initial stage of wound repair following elastase-mediated proteolysis action. Among the peptides generated, those having a x.G.x.x.P.G. motif upregulate (i) keratinocyte migration, (ii) endothelial cell angiogenic phenotype, (iii) fibroblast proliferation, and (iv) induction of the expression of matrix metalloproteinases, type I collagen, and tropoelastin. All of these properties could accelerate the different stages of wound repair. Elastin-derived peptides from a chemical or a proteolytic digest of insoluble elastin alone or linked to the collagen scaffold significantly improve skin wound healing and dermal regeneration in vivo in several animal models. Such a beneficial influence has been recently extended to the treatment of burn patients. In this respect, recent investigations have focused on the design of elastin-derived peptides or elastin-building blocks, as obtained from peptide chemistry or by genetic engineering, to elaborate biocompatible elastin peptides, which are considered as ideal biomaterials for "catalyzing" skin repair and regeneration following injury.
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PMID:Role of the elastin receptor complex (S-Gal/Cath-A/Neu-1) in skin repair and regeneration. 1976 16


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