Working Model for the Regulation of the SPIK Channel by the CPK11 and CPK24 Signaling Cascade in Arabidopsis Pollen Tubes.
CPK11 and CPK24 are involved in the Ca2+-dependent regulation of the K+in channels in Arabidopsis pollen tubes. During pollen tube growth, cytoplasmic Ca2+ elevation activates CPK11, and the activated CPK11 subsequently phosphorylates CPK24. This kinase cascade transduces the calcium signals and regulates SPIK activity and pollen tube growth.