Analysis of a Receptor-Like Protein Kinase of Arabidopsis Thaliana
Genomic and cDNA clones encoding a novel receptor-like protein kinase (TMK1) have been isolated from Arabidopsis thaliana. The predicted protein has an intracellular kinase domain most related to the receptor tyrosine kinases but containing diagnostic serine/threonine sequences, a transmembrane domain, and an extracellular domain containing 11 copies of a leucine rich repeat. Leucine rich repeats have only been found in proteins associated with the plasma membrane and are involved in protein/protein interactions. Domain-specific antibodies against the extracellular and intracellular domains of TMK1 have been made using fusion proteins expressed in E. coli. In extracts of Arabidopsis, the antibodies specifically immunodecorate a polypeptide of about 120 kD. The native TMK1 protein from Arabidopsis is capable of reversible binding to lectin columns, and digestion with endoglycosidase F reduces the apparent molecular mass of the immunodecorated protein by 10 kD, indicating that the native protein is glycosylated. The intracellular domain of TMK1 was expressed as a fusion protein with maltose binding protein in E. coli and was found capable of autophosphorylation on serine and threonine residues, indicating that the intracellular domain of TMK1 is a functional protein kinase.
KeywordsExtracellular Domain Kinase Domain Maltose Binding Protein Leucine Rich Repeat Domain Receptor Protein Kinase
Unable to display preview. Download preview PDF.
- Chang, C., Schaller, G.E., Patterson, S.E., Kwok, S.F., Meyerowitz, E.M., and Bleecker, A.B., 1992, The TMK1 gene from Arabidopsis codes for a protein with structural and biochemical characteristics of a receptor protein kinase, Plant Cell (in press).Google Scholar
- Crass, J.W., 1991, Cycling of auxin-binding protein through the plant cell: pathways in auxin signal transduction, New Biologist 3:813.Google Scholar
- Romberg, J.M., Jacobs, J.R., Goodman, C.S., and Artavanis-Tsakonas, S., 1990, slit: An extracellular protein necessary for development of midline glia and commissural axon pathways contains both EGF and LRR domains, Genes Dev. 4:2169.Google Scholar