C. Domingo et al., A NOVEL EXTRACELLULAR-MATRIX PROTEIN FROM TOMATO ASSOCIATED WITH LIGNIFIED SECONDARY CELL-WALLS, The Plant cell, 6(8), 1994, pp. 1035-1047
A cDNA clone representing a novel cell wall protein was isolated from
a tomato cDNA library. The deduced amino acid sequence shows that the
encoded protein is very small (88 amino acids), contains an N-terminal
hydrophobic signal peptide, and is enriched in lysine and tyrosine. W
e have designated this protein TLRP for tyrosine- and lysine-rich prot
ein. RNA gel blot hybridization identified TLRP transcripts constituti
vely present in roots, stems, and leaves from tomato plants. The encod
ed protein seems to be highly insolubitized in the cell wall, and we p
resent evidence that this protein is specifically localized in the mod
ified secondary cell walls of the xylem and in cells of the sclerenchy
ma, In addition, the protein is localized in the protective periderm l
ayer of the growing root. The highly localized deposition in cells des
tined to give support and protection to the plant indicates that this
cell wall protein alone and/or in collaboration with other cell wall s
tructural proteins may have a specialized structural function by mecha
nically strengthening the walls.