CHARACTERIZATION OF AN ARABIDOPSIS-THALIANA GENE (TMKL1) ENCODING A PUTATIVE TRANSMEMBRANE PROTEIN WITH AN UNUSUAL KINASE-LIKE DOMAIN

We have characterized a novel Arabidopsis gene, designated TMKL1 (for Transmembrane Kinase-Like). The encoded protein is predicted to contai n an N-terminal signal peptide, an extracellular domain with seven imp erfect leucine-rich repeats, a single hydrophobic transmembrane segmen t, and a kinase-like intracellular domain which lacks, however, severa l of the key conserved residues essential for catalytic activity. The TMKL1 protein thus represents a unique and functionally intriguing mem ber of the family of plant proteins related to animal receptor kinases . Northern blot analysis indicates that the TMKL1 gene is transcriptio nally active in a variety of organs, and is developmentally regulated during silique maturation. Its possible functions are discussed.