Isolation, characterization and immunolocalization of a novel, modular tomato arabinogalactan-protein corresponding to the LeAGP-1 gene.
Arabinogalactan-proteins (AGPs) are a family of hydroxy-proline-rich glycoproteins implicated to function in plant growth and development. This report focuses on a novel, modular AGP found in tomato, LeAGP-1, which was predicted by DNA cloning and herein verified at the protein level as a major AGP component. LeAGP-1 was isolated from tomato suspension-cultured cells and verified to be an AGP by precipitation with (beta-D-galactosyl)3 Yariv phenylglycoside and by amino acid composition analysis. Furthermore, LeAGP-1 was determined to correspond to LeAGP-1 clones based on three criteria: (1) amino acid composition identity, (2) amino acid sequence identity, and (3) specific immunoreactivity of glycosylated and deglycosylated LeAGP-1 with an antibody developed against the highly basic subdomain predicted from LeAGP-1 clones. The antibody was also used to immunolocalize LeAGP-1 in tomato to the cell surface of suspension-cultured cells, maturing metaxylem elements in young internodes and petioles, and stylar transmitting tissue cells. At the subcellular level, LeAGP-1 immunolocalized to the cell walls of these particular cells as well as to intercellular spaces between stylar transmitting tissue cells. LeAGP-1 now emerges as one of the most comprehensively studied AGPs in terms of (1) characterization at the genomic DNA, cDNA and protein levels, (2) known organ-specific and developmentally regulated mRNA expression patterns, (3) development of an antibody against a unique, peptide subdomain which specifically recognizes LeAGP-1 in its glycosylated and deglycosylated states, and (4) immunolocalization of a single, well-defined AGP molecule at the tissue and subcellular levels.
Gao
M
M
Department of Environmental and Plant Biology, Ohio University, Athens 45701-2979, USA.
Kieliszewski
M J
MJ
Lamport
D T
DT
Showalter
A M
AM
D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D002473:Cell Wall / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D007150:Immunohistochemistry; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011817:Rabbits
D018076:DNA, Complementary; D018744:DNA, Plant; D009088:Mucoproteins; D010940:Plant Proteins; C006619:arabinogalactan proteins