Abstract
Proteins included in the CDPK/CPK-SnRK (calcium-dependent protein kinase-SNF1-related kinase) superfamily or CBL (calcineurin B-like protein) participate in the regulation of stomatal aperture and ion uptake by modulating the activity of transporter or channels. Addition of lipid on the proteins is one of the important post-translational modifications involved in the protein regulation. The Arabidopsis CPKs contain myristoylation motifs at their N termini. To evaluate the occurrence of myristoylation on the 29 of CPKs in vitro, we synthesized them using in vitro translation system both from insect cell extract and wheat germ extract. Most CPKs analyzed were myristoylated in vitro. Some of SnRKs among Arabidopsis 38 different SnRKs possess the myristoylation motifs, but they did not have any myristoylation form in in vitro system. Arabidopsis CBL1, CBL4, CBL5, and CBL9 contain the motifs for myristoylation at the N termini. We translated these CBLs in vitro and we found that all four CBLs were myristoylated. These data provides the information on the possible membrane-associated CPKs and CBLs, some of which may interact and regulate the transporters and channels on the membrane.
