Glycine-rich proteins as structural components of plant cell walls

Abstract

Glycine-rich proteins (GRPs) have been found in the cell walls of many higher plants and form a third group of structural protein components of the wall in addition to extensins and proline-rich proteins. The primary sequences of GRPs contain more than 60% glycine. GRPs are localized mainly in the vascular tissue of the plant, and their coding genes provide an excellent system to analyze the molecular basis of vascular-specific gene expression. In French bean, the major cell wall GRP has been localized at the ultrastructural level in the modified primary cell wall of protoxylem. Immunological studies showed that it forms a major part of these highly extensible and specialized cell walls. Specific digestion of GRP1.8 from bean by collagenase suggests that it shares structural similarities with collagen. The protein is synthesized by living protoxylem cells as well as xylem parenchyma cells. After cell death, GRPs are exported from neighboring xylem parenchyma cells to the protoxylem wall, a rare example of protein transport between cells in plants. We propose that GRPs are part of a repair system of the plant during the stretching phase of protoxylem.

Auxin Metabolism and Function in the Multicellular Brown AlgaEctocarpus siliculosus

“…In the C-terminal part of the sequence, 10 repeated Gly-rich sequences were clustered, separated by several hydrophilic sequences of eight to 19 amino acids. In land plants, extensins are Hyp-rich proteins present in the extracellular matrix, where they are thought to play a role in plant cell wall stiffness (Kieliszewski and Lamport, 1994), and Glyrich proteins are secreted proteins involved in adhesion and extension of differentiating vascular cells (Ringli et al, 2001).…”

Cell wall proteins: a new insight through proteomics

“…Molecular biology techniques and the complete sequencing of the Arabidopsis thaliana genome greatly contributed to the description of many CWP gene families and their transcriptional regulation [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. It was found that most CWP are encoded by multigene families.…”

Global Identification of Target Genes Regulated by APETALA3 and PISTILLATA Floral Homeotic Gene Action

“…The anther development gene ATA20 (At3g15400; group D) was identified previously as stamen specific (Rubinelli et al, 1998). It encodes a protein containing a Gly-rich region that is characteristic of one of the groups of cell wall proteins (Sachetto-Martins et al, 2000; Ringli et al, 2001). The second gene encodes an arabinogalactan protein, AGP6 (At5g14380; group D).…”