Molecular cloning of a gene encoding an arabinogalactan-protein from pear (Pyrus communis) cell suspension culture.
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.
Chen
C G
CG
Cooperative Research Centre for Industrial Plant Biopolymers, University of Melbourne, Parkville, Victoria, Australia.
Pu
Z Y
ZY
Moritz
R L
RL
Simpson
R J
RJ
Bacic
A
A
Clarke
A E
AE
Mau
S L
SL
D000595:Amino Acid Sequence; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular / Q000379:methods; D018076:DNA, Complementary; D005638:Fruit / Q000378:metabolism*; D015870:Gene Expression; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010940:Plant Proteins / Q000096:biosynthesis; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000096:biosynthesis / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification
D018076:DNA, Complementary; D009088:Mucoproteins; D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments; D010940:Plant Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C006619:arabinogalactan proteins