Proteoglycans and Related Components in Plant Cells

Nothnagel, Eugene A.

doi:10.1016/s0074-7696(08)62118-x

Cited by 359 publications

(334 citation statements)

References 274 publications

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“…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%

“…Evidence for galactosyl-O-Hyp, galactosyl-OSer, and arabinosyl-O-Hyp and unidentified glycosyl residues linked to Thr are reported for several AGPs [29]. Based on the Hyp-contiguity hypothesis, which briefly states that contiguous Hyp residues are glycosylated with oligoarabinosides, whereas single noncontiguous Hyp residues are glycosylated with polysaccharide units, glycosylation patterns can be predicted for AGP core protein sequences [31].…”

Section: Carbohydrate-core Protein Linkagesmentioning

confidence: 99%

“…Some AGPs are present in multivesicular bodies, and this has led to the suggestion that these AGPs are destined for degradation in the vacuole [38,39]. Several plant glycosidases (e. g., a-L-arabinofuranosidases, b-galactosidases) are known which could theoretically break down AGPs; however, direct testing of these enzymes on AGP substrates and determining conclusive cellular localizations for them remain to be performed [29]. Such processing events may represent important ways in which AGP functions are regulated.…”

Section: Processing Of Agps and Gpi Anchorsmentioning

confidence: 99%

“…Although this early survey work was largely based on positive reactivity of plant extracts or tissue sections with Yariv reagent, other tools were subsequently used to confirm that numerous angiosperms, gymnosperms and lower plants (e. g. bryophytes, algae) contain AGPs [29,40,[59][60][61]. …”

Section: Agp Expression In the Plant Kingdommentioning

confidence: 99%

“…At the organ level, AGPs are found in leaves, stems, roots, floral parts and seeds [29,40]. Similarly, AGPs are found in many tissues, and are especially abundant and well documented in xylem, stylar transmitting tissue and cell suspension cultures.…”

Section: Agp Expression In Plant Organs and Tissuesmentioning

confidence: 99%

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Arabinogalactan-proteins: structure, expression and function

Showalter

2001

CMLS, Cell. Mol. Life Sci.

518

464

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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.

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Section: Carbohydrate Moietymentioning

confidence: 99%

Section: Carbohydrate-core Protein Linkagesmentioning

confidence: 99%