Form and function of arabinogalactans and arabinogalactan-proteins

Clarke, Adrienne E.; Anderson, Robin L.; Stone, BA

doi:10.1016/s0031-9422(00)84255-7

Cited by 446 publications

(210 citation statements)

References 212 publications

Supporting

Mentioning

201

Contrasting

Unclassified

Order By: Relevance

“…The protein content was comparable to that found in proteoglycans of human synovial fluid [21], cartilage [22] or plant arabinogalactans [23,24]. Analyzed by SDS-PAGE the glycogen fraction of retina showed a unique band stained by Coomassie blue.…”

Section: Isolation Of I-labeled Gl?jcogetipeptitkcsupporting

confidence: 62%

Evidence for the glycoprotein nature of retina glycogen

Aon

Curtino

1984

Eur J Biochem

View full text Add to dashboard Cite

Incubation of a bovine retina membrane preparation with micromolar amounts of UDP-['4C]glucose resulted in the incorporation of [14C]glucose into endogenous (1 +4)-a-glucan, insoluble in trichloroacetic acid, and acidsoluble ethanol-insoluble glycogen.1. The trichloroacetic-acid-insoluble glucan fraction of retina migrated in 2.6 -3 % acrylamide gels when subjected to sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) and was rendered acidsoluble by digestion with pronase.2. The solubility of the acid-insoluble glucan in acidified organic solvent was different from that of amylose or glycogen and similar to membrane proteins and glycoproteins.3. The glycogen fraction of retina contained 1.5 -2.0 pg protein/lOO pg glucose. When this fraction was analyzed by SDS-PAGE only one band, which moved near the top of 3 % acrylamide gels, was stained with periodic acid Schiff reagent and Coomassie blue. 4. The protein nature of the Coomassie-blue-stainable material was demonstrated by iodination of the glycogen fraction with [1311]iodide and identification of labeled monoiodotyrosine and diiodotyrosine. The bulk of the label comigrated with carbohydrate near the top of gels in SDS-PAGE and treatment with a-amylse decreased the molecular size of both labeled and stainable material. 5.Physical dissociative conditions (7.5 M ureaj0.83 SDSj0.83 % mercaptoethanol) and the following chemical treatments failed to dissociate the iodinated protein from glycogen: (a) 0.1 M NaOH/O.l M NaBH, at room temperature for 24 h; (b) 1 M HCl in methanol at 50 "C for 10 min; (c) trifluoroacetic acid at 50 "C for 6 min.6. 1311-labeled glycogenpeptide was isolated after 1311-labeled protein-bound glycogen had been subjected to digestion with papain/pronase and passed through a Sepharose column.7. The results suggest that at least part of glycogen in bovine retina is firmly combined to protein as a single proteoglycogen molecule. Furthermore some of the proteoglycogen might be present as a trichloroacetic-acidprecipitable proteoglucan owing to its lower glucose content.The synthesis of (1 -+4)-a-glucan, bound to protein, has been inferred from results obtained in vitro in several systems such as rat liver [l], Escherichia coli [2], Neurospora crassa [3], potato tuber [4] and bovine retina [5]. The presence of protein linked to glucan was argued from the insolubility in trichloroacetic acid and sensitivity to pronase of the synthesized products. However, unbranched long glucan chains are intrinsically insoluble in trichloroacetic acid [6]. The materials released by pronase were not further analyzed and controls for the possible presence of contamihating amylolytic activity in the protease preparations were not shown.Evidence for protein strongly bound to glucan was claimed after dinitrophenylation of a 'glycogen-peptide' obtained from a trichloroacetic acid-insoluble glucan fraction of liver [7], but no dinitrophenylated amino acid was demonstrated.In the present work the attempt to demonstrate protein firmly combined to (1 +4)-a-...

show abstract

Section: Isolation Of I-labeled Gl?jcogetipeptitkcsupporting

confidence: 62%

Evidence for the glycoprotein nature of retina glycogen

Aon

Curtino

1984

Eur J Biochem

View full text Add to dashboard Cite

show abstract

“…The arabinose and galactose residues are arranged in polysaccharide units that are attached to multiple sites on the core protein. [28,29]. Short arabinose oligosaccharide chains additionally decorate at least some AGPs, just as they do in the extensins [6,30].…”

Section: Carbohydrate Moietymentioning

confidence: 99%

“…Notably, all three of these clones have a repeated nucleotide sequence motif in their respective 3¢ untranslated sequences, which is associated with rapid turnover of mRNAs. It also should be noted that gum arabic AGP is secreted only upon wounding, and this secretion occurs only at the wound site [28]. Other factors, including treatment with various plant hormones and pathogen infection, also may serve to regulate AGP expression, but remain to be investigated.…”

Section: Agp Expression In Plant Organs and Tissuesmentioning

confidence: 99%

Arabinogalactan-proteins: structure, expression and function

Showalter

2001

CMLS, Cell. Mol. Life Sci.

517

460

View full text Add to dashboard Cite

Abstract. Arabinogalactan-proteins (AGPs) are a family of extensively glycosylated hydroxyproline-rich glycoproteins that are thought to have important roles in various aspects of plant growth and development. After a brief introduction to AGPs highlighting the problems associated with defining and classifying this diverse family of glycoproteins, AGP structure is described in terms of the protein component (including data from molecular cloning), carbohydrate component, processing of AGPs (including recent data on glycosylphosphatidylinositol membrane anchors) and overall molecular shape. Next, the expression of AGPs is examined at several different levels, from the whole plant to the cellular levels, using a variety of experimental techniques and tools. Finally, AGP function is considered. Although the existing functional evidence is not incontrovertible, it does clearly droxyproline poor, lightly glycosylated and largely unreactive with Yariv reagent. It is worth remembering that it is human nature to group and classify things to facilitate their comprehension and discourse, whereas Mother Nature simply constructs biological entities, including AGPs, using material at hand with blatant, pedagogical disregard. Structure Protein moietyKnowledge of the protein moieties of AGPs has mostly come from purifying AGPs, deglycosylating them and analyzing their respective core proteins by amino acid analysis and, to a more limited extent, by sequence analysis ( fig. 2) [3 -10]. More recently, molecular cloning of several confirmed and putative AGP core proteins has CMLS, Cell. Mol. Life Sci. 58 (2001) 1399 -1417 1420-682X/01/101399-19 $ 1.50 + 0.20/0 © Birkhäuser Verlag, Basel, 2001 CMLS Cellular and Molecular Life Sciences point to roles for AGPs in vegetative, reproductive, and cellular growth and development as well as programmed cell death and social control. In addition and most likely inextricably linked to their functions, AGPs are presumably involved in molecular interactions and cellular signaling at the cell surface. Some likely scenarios are discussed in this context. AGPs also have functions of real or potential commercial value, most notably as emulsifiers in the food industry and as potential immunological regulators for human health. Several important questions remain to be answered with respect to AGPs. Clearly, elucidating the unequivocal functions of particular AGPs and relating these functions to their respective structures and modes of action remain as major challenges in the years ahead.

show abstract

“…Further, these intriguing results seem to support a developmental role for this family of proteins, and since, in angiosperms, secreted AGPs are a major constituent of the extracellular matrix of transmitting tissue, it has been proposed that they have a nutritive role in pollen tube growth and/or assist pollen adhesion to the stigma in species possessing 'wet" stigmatic tissues (Labarca and Loewus, 1972;Clarke et al, 1979;Gell et al, 1986). There also is evidence of the accumulation of AGPs in response to wounding, which suggests a possible role for these molecules in plant defense (Fincher et al, 1983;Showalter and Varner, 1989).…”

mentioning

confidence: 89%

A Novel Hydroxyproline-Deficient Arabinogalactan Protein Secreted by Suspension-Cultured Cells of Daucus carota (Purification and Partial Characterization)

1993

View full text Add to dashboard Cite

Arabinogalactan proteins (ACPs) are secreted or membraneassociated glycoproteins that have been operationally defined as binding to ,9-glucosyl Yariv artificial antigen, being rich in arabinose and galactose, and containing high levels of alanine, serine, and hydroxyproline. Using an anti-ACP monoclonal antibody (MAC 207) bound to cyanogen bromide-activated Sepharose 46, we have purified by immunoaffinity chromatography an extracellular ACP from the culture medium of suspension-cultured cells of carrot (Daucus carota). The apparent molecular mass of this highly glycosylated proteoglycan is 70 to 100 kD as judged by sodium dodecyl sulfate-polyacrylamide gels. Although its sugar analysis, j3-glucosyl Yariv binding, and high alanine, serine, and proline content are consistent with it being an AGP, the amino acid composition unexpectedly revealed this molecule to have no detectable hydroxyproline. This suggests that this glycoprotein is not a "classical" ACP, but represents the first example of a new class of hydroxyproline-poor ACPs. Deglycosylation of the ACP with anhydrous hydrogen fluoride revealed that the purified proteoglycan contains probably a single core protein with an apparent molecular mass of 30 kD. Direct visualization of the native ACP in the electron microscope showed ellipsoidal putative ACP monomers, approximately 25 nm by 15 nm, that showed a strong tendency to self assemble into higher-order structures. Upon desiccation, the glycosylated ACP formed paracrystalline arrays visible in the light microscope. Polarized Fourier transform infrared microspectroscopy of these arrays demonstrated a high degree of polarization of the sugar moieties under these conditions. These results put possible constraints on current models of ACP structure; a putative role for these nove1 AGPs as pectin-binding proteins is discussed.

show abstract

Form and function of arabinogalactans and arabinogalactan-proteins

Cited by 446 publications

References 212 publications

Evidence for the glycoprotein nature of retina glycogen

Evidence for the glycoprotein nature of retina glycogen

Arabinogalactan-proteins: structure, expression and function

A Novel Hydroxyproline-Deficient Arabinogalactan Protein Secreted by Suspension-Cultured Cells of Daucus carota (Purification and Partial Characterization)

Contact Info

Product

Resources

About