The activator of cerebroside sulphatase binding studies with enzyme and substrate demonstrating the detergent function of the activator protein

Fischer, G.; Jatzkewitz, Horst

doi:10.1016/0005-2744(77)90288-1

Cited by 83 publications

(31 citation statements)

References 18 publications

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“…Thereby also the tightly membrane-bound long-chain lactosylceramide is lifted from the lipid bilayer and hydrolyzed by the enzyme either at the surface of the lipid bilayer or in solution. Similar mechanisms were proposed previously for the action of sup-B by Fischer and Jatzkewitz [4] and for the GM2 activator by Conzelmann and Sandhoff [33]. LacCer analogues with short acyl chains, being more hydrophilic than long-chain analogues, are degraded faster (Fig.…”

Section: Discussionsupporting

confidence: 76%

“…These complexes were recognized by GM1-P-galactosidase as optimal substrates in the same mode, as postulated for the hydrolysis of sulfatides by arylsulfatase A [Fischer, G. and Jatzkewitz, H. (1977) Biochim. Biophys.…”

mentioning

confidence: 56%

“…The naturally occurring long-chain C,, analogue was hydrolyzed to a measurable extent only in the presence of sup-B. According to the model of Fischer and Jatzkewitz [4], in this case the optimal substrate for the enzymic reaction is the activator-lipid complex which increases proportionally with the activator concentration used. Since the rather low concentrations of the labile and transient complexes between activator and the different lactosylceramide analogues cannot be assayed readily in the reaction mixtures with liposomes, we determined the activator concentrations needed for half-maximal reaction velocities by varying the concentrations of sup-B and keeping the concentrations of liposomal lactosylceramides constant.…”

Section: Hydrolysis Of Liposomal Ganglioside Gm1 and Lactosylceramidementioning

confidence: 99%

“…The inherited deficiency of sup-B causes accumulation of sulfatides and some other sphingolipids in a variant of metachromatic leukodystrophy (for review see [2]). sup-B binds sulfatides, lifts them from micellar or liposomal surfaces and presents them to the water-soluble arylsulfatase [4,51. Sulfatide analogues with truncated acyl chains are hydrolyzed by arylsulfatase in the absence of sup-B [5], presumably because they are less tightly bound to micellar or liposomal structures.…”

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confidence: 99%

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Hydrolysis of lactosylceramide by human galactosylceramidase and GM1‐β‐galactosidase in a detergent‐free system and its stimulation by sphingolipid activator proteins, sap‐B and sap‐C Activator proteins stimulate lactosylceramide hydrolysis

Zschoche

Fürst

Schwarzmann

et al. 1994

European Journal of Biochemistry

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Two exo-P-galactosidases are involved in the lysosomal degradation of glycosphingolipids : GM1-P-galactosidase (EC 3.2.1.23) and galactosylceramidase (EC 3.2.1.46). Analyses were performed with both enzymes, using lactosylceramides with varying acyl chain lengths as substrates that were inserted into unilamellar liposomes and naturally occurring sphingolipid activator proteins sup-B and sup-C, rather than detergents, to stimulate the reaction.While sup-B was a better activator for the reaction catalyzed by GM1-P-galactosidase, sup-C preferentially stimulated lactosylceramide hydrolysis by galactosylceramidase. The enzymic hydrolysis of liposome-integrated lactosylceramides was significantly dependent on the structure of the lipophilic aglycon moiety of the lactosylceramide decreasing with increasing length of its fatty acyl chain (C, > C, > C, > C, > Clo> C,J. However, in the presence of detergents the degradation rates were independent of the acyl chain length. Hydrolysis of liposomal lactosylceramide was compared with sup-B-stimulated hydrolysis of liposomal ganglioside GM1 by GM1-P-galactosidase and sup-C-stimulated degradation of liposomal galactosylceramide by galactosylceramidase.Kinetic and dilution experiments indicated that sup-B forms water-soluble complexes with both lactosylceramide and GM1. These complexes were recognized by GM1-P-galactosidase as optimal substrates in the same mode, as postulated for the hydrolysis of sulfatides by arylsulfatase A [Fischer, G. and Jatzkewitz, H. (1977) Biochim. Biophys. A m 481,561 -5721. GM1-P-galactosidase was more active on these complexes than on glycolipids (GM1 and lactosylceramides) still residing in liposomal membranes. On the other hand, dilution experiments indicated that degradation of galactosylceramide and lactosylceramide by galactosylceramidase proceeds almost exclusively on liposomal surfaces : both activators, sup-C and sup-B, stimulated the hydrolysis of lactosylceramide analogues with long acyl chains more than the hydrolysis of lactosylceramides with short acyl chains.Glycosphingolipids are primarily components of the outer leaflet of plasma membranes. Their biosynthesis occurs in the endoplasmic reticulum and Golgi compartment, their degradation mainly in lysosomes [l]. A recent hypothesis on Correspondence to K. Sandhoff, Institut fur Organische Chemie und Biochemie, Universitat Bonn, Gerhard-Domagk-Stral3e 1, D-53121 Bonn, GermanyAbbreviations. Cer, ceramide ; LacCer, lactosylceramide, Galbl4GlcP1-1 Cer ; C,-LacCer, N-acetyl-(1-0-lactosyl) sphingosine; C,-LacCer, N-butanoyl-(1-0-lactosyl) sphingosine ; C,-LacCer, N-hexanoyl-(1-0-lactosyl) sphingosine; C,-LacCer, N-octanoyl-(1-0-lactosyl) sphingosine; C,,-LacCer, N-decanoyl-(1-0-lactosyl) sphingosine; C,,-LacCer, N-octadecanoyL(1-0-lactosyl) sphingosine; GalCer, galactosylceramide, Galbl-1 Cer ; GM1, Galj?l-3GalNAcj?l4Gal(3-2aNeuAc)~1-4Glc/?l-l Cer ; sup-B, sulfatide activator protein or SAP-1 or saposin B, sphingolipid activator protein B; sup-C, co-p-glucosidase or SAP-2 or saposin C, sphing...

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Section: Discussionsupporting

confidence: 76%

mentioning

confidence: 56%

Section: Hydrolysis Of Liposomal Ganglioside Gm1 and Lactosylceramidementioning

confidence: 99%

mentioning

confidence: 99%

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Hydrolysis of lactosylceramide by human galactosylceramidase and GM1‐β‐galactosidase in a detergent‐free system and its stimulation by sphingolipid activator proteins, sap‐B and sap‐C Activator proteins stimulate lactosylceramide hydrolysis

Zschoche

Fürst

Schwarzmann

et al. 1994

European Journal of Biochemistry

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“…The identity of their activator for degradation of ganglioside G,, with the preparation described in this work has not yet been examined; however, they appear to be quite similar, in spite of the fact that the authors, based on their preliminary experiments, postulate a different mechanism [34]. Conversely, the activator for breakdown of ganglioside G,, of Li and Li [26], as well as the sulphatide activator of Fischer and Jatzkewitz [25], were found to be without effect on the degradation of ganglioside GMZ by hexosaminidase A [35]. Also, the pathology and the lipid storage pattern found in patients of variant AB of infantile G,, gangliosidosis [Is], which is caused by the defiency of the activator protein for ganglioside G,, catabolism [14], strongly suggest that this activator is essential only for the degradation of glycolipid substrates of hexosaminidase A but not for the degradation of other glycolipids.…”

Section: Discussionmentioning

confidence: 96%

Complexing of Glycolipids and Their Transfer between Membranes by the Activator Protein for Degradation of Lysosomal Ganglioside G_M2

Conzelmann

Burg

Günther

et al. 1982

European Journal of Biochemistry

150

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The lysosomal degradation of ganglioside G M Z by hexosaminidase A depends on the presence of the specific activator protein which mediates the interaction between micellar or membrane-bound ganglioside and water-soluble hydrolase. The mechanism and the glycolipid specificity of this activator were studied in more detail.1. It could be shown with three different techniques (isoelectric focusing, centrifugation and electrophoresis) that the activator protein extracts glycolipid monomers from micelles or liposomes to give water-soluble complexes with a stoichiometry of 1 mol of glycolipid/mol of activator protein. Liposome-bound ganglioside C,, is considerably more stable against extraction and degradation than micellar ganglioside.2. In the absence of enzyme the activator acts in vitro as glycolipid transfer protein, transporting glycolipids from donor to acceptor membranes.3. The activator protein is rathcr specific for ganglioside GM2. Other glycolipids (GM3, G M I , GDla and GA2) form less stable complexes with the activator and are transferred at a slower rate (except for ganglioside G, than ganglioside GM,The catabolism of glycolipids is accomplished by the sequential action of acid lysosomal glycosidases [I -51. An 'inherited deficiency of one of these enzymes results in the accumulation of all of its substrates, leading to the clinical picture of a lipidosis [2 -61. To study the pathogenesis of these diseases, a number of the enzymes involved have been purified and studied in vitro (cf. [4, 51). It was found that the watersoluble enzymes, such as the hexosaminidases, were active on water-soluble substrates, but had hardly any effect on their putative lipid substrates, owing to the latter's aggregation. In vitro, this difficulty can be overcome by the addition of suitable detergents [7-1 I]. In human tissues, proteins have been identified that facilitate the interaction between water-soluble enzymes and their lipid substrates [12, 131. The physiological importance of these 'activator' proteins is demonstrated by the finding that fatal glycolipid accumulation in variant AB of infantile GM2 gangliosidosis is caused by the deficiency of the activator protein for the degradation of ganglioside GMZ by hexosaminidase A [14]. The purification and partial characterization of this protein has been reported [15]. In the present paper the mechanism by which the activator stimulates ganDedicated to Professor Horst Jatzkewitz on the occasion of his 70th birthday.Ahhreviatiorm. Cer, ceramide or N-acylsphingoid; Gal, D-galactose; GalNAc, 2-acetamido-2-deoxy-~-galactopyranose; Glc, D-glucose; GlcNAc, 2-acetamido-2-deoxy-~-glucopyranose; Lac, lactose; NeuAc, N-acetylneuraniinic acid ; GAZ or glycosphingolipid GAZ, GgOseJCer or GalNAcp1 +4Galp1 +4Glc/j1-*1 Cer; G,,, or ganglioside G,,,, I13NeuAc,lV3NeuAc-GgOse4Cer or Gal(3t2ctNeuAc)fii +3GalNAcfi1 -4Ga1(3 t 2~N e u A c ) f i l --t 4Glc/31 4 1Cer; G,, or ganglioside G,,, I13NeuAc-GgOse,Cer or Galpl + 3GalNAcfl1+ 4Ga1(3 + 2xNeuAc)fil -4Glc/31 +ICer; GMZ or ganglioside GMZ, II3...

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Cerebroside sulfate activator protein (Saposin B): chromatographic and electrospray mass spectrometric properties

Faull¹,

Whitelegge²,

Higginson³

et al. 1999

J. Mass Spectrom.

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The activator of cerebroside sulphatase binding studies with enzyme and substrate demonstrating the detergent function of the activator protein

Cited by 83 publications

References 18 publications

Hydrolysis of lactosylceramide by human galactosylceramidase and GM1‐β‐galactosidase in a detergent‐free system and its stimulation by sphingolipid activator proteins, sap‐B and sap‐C Activator proteins stimulate lactosylceramide hydrolysis

Hydrolysis of lactosylceramide by human galactosylceramidase and GM1‐β‐galactosidase in a detergent‐free system and its stimulation by sphingolipid activator proteins, sap‐B and sap‐C Activator proteins stimulate lactosylceramide hydrolysis

Complexing of Glycolipids and Their Transfer between Membranes by the Activator Protein for Degradation of Lysosomal Ganglioside G_M2

Cerebroside sulfate activator protein (Saposin B): chromatographic and electrospray mass spectrometric properties

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The activator of cerebroside sulphatase binding studies with enzyme and substrate demonstrating the detergent function of the activator protein

Cited by 83 publications

References 18 publications

Hydrolysis of lactosylceramide by human galactosylceramidase and GM1‐β‐galactosidase in a detergent‐free system and its stimulation by sphingolipid activator proteins, sap‐B and sap‐C Activator proteins stimulate lactosylceramide hydrolysis

Hydrolysis of lactosylceramide by human galactosylceramidase and GM1‐β‐galactosidase in a detergent‐free system and its stimulation by sphingolipid activator proteins, sap‐B and sap‐C Activator proteins stimulate lactosylceramide hydrolysis

Complexing of Glycolipids and Their Transfer between Membranes by the Activator Protein for Degradation of Lysosomal Ganglioside GM2

Cerebroside sulfate activator protein (Saposin B): chromatographic and electrospray mass spectrometric properties

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Complexing of Glycolipids and Their Transfer between Membranes by the Activator Protein for Degradation of Lysosomal Ganglioside G_M2