Diverse Plant Protein Kinases with Calmodulin-Like Domains
Plants respond to many stimuli such as drought, heat, cold, hormones, insects, and pathogens with intracellular calcium fluxes. These calcium signals are then decoded by a diverse family of calcium-dependent protein kinases (CDPKs) with calmodulin-like domains. The question, then, is how the CDPKs generate appropriate responses to these different stimuli that all evoke calcium as a second messenger.
Our work with CDPKs began with a CDPK isoform and a CDPK-related kinase (CRK) cloned from carrot somatic embryos, and has continued with new CRK isoforms cloned from the model plant, Arabidopsis thaliana. CDPK431 is a canonical CDPK with 4 EF-hands in its calmodulin- like domain (Suen and Choi, 1991). CRK421 has no consensus EF-hand motifs (Lindzen and Choi, 1995). We are looking at possible modes of regulation of these kinases, by calcium, lipids, membrane localization, and interactions with other proteins. Long-term, we are also interested in characterizing specific substrates for these kinases.