Isolation, characterization and immunolocalization of a novel, modular tomato arabinogalactan-protein corresponding to the LeAGP-1 gene
Article first published online: 5 JAN 2002
The Plant Journal
Volume 18, Issue 1, pages 43–55, April 1999
How to Cite
Gao, M., Kieliszewski, M. J., Lamport, D. T. A. and Showalter, A. M. (1999), Isolation, characterization and immunolocalization of a novel, modular tomato arabinogalactan-protein corresponding to the LeAGP-1 gene. The Plant Journal, 18: 43–55. doi: 10.1046/j.1365-313X.1999.00428.x
- Issue published online: 5 JAN 2002
- Article first published online: 5 JAN 2002
- Received 18 December 1998; accepted 5 February 1999.
Arabinogalactan-proteins (AGPs) are a family of hydroxyproline-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 (β-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.