Open AccessMolecular cloning of a gene encoding an arabinogalactan-protein from pear (Pyrus communis) cell suspension culture.
Author(s) -
Chao-Guang Chen,
Zhao-Yan Pu,
Robert L. Moritz,
Richard J. Simpson,
Antony Bacic,
Adrienne E. Clarke,
Shaio-Lim Mau
Publication year - 1994
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.91.22.10305
Subject(s) - arabinogalactan , biochemistry , complementary dna , signal peptide , amino acid , transmembrane domain , peptide sequence , biology , gene , polysaccharide
Arabinogalactan-proteins (AGPs) are proteoglycans containing a high proportion of carbohydrate (typically > 90%) linked to a protein backbone rich in hydroxyproline (Hyp), Ala, Ser, and Thr. They are widely distributed in plants and may play a role in development. The structure of the carbohydrate of some AGPs is known in detail but information regarding the protein backbone is restricted to a few peptide sequences. Here we report isolation and partial amino acid sequencing of the protein backbone of an AGP. This AGP is a member of one of four major groups of AGPs isolated from the filtrate of pear cell suspension culture. A cDNA encoding this protein backbone (145 amino acids) was cloned; the deduced protein is rich in Hyp, Ala, Ser, and Thr, which together account for > 75% of total residues. It has three domains, an N-terminal secretion signal, a central hydrophilic domain containing all of the Pro residues, and a hydrophobic C-terminal domain that is predicted to be a transmembrane helix. Approximately 93% of the Pro residues are hydroxylated and hence are potential sites for glycosylation.