The Harper lab is interested in how a plant can use as few as 28,000 genes to develop and survive under extreme environmental conditions, such as cold, heat, drought and salt stress. A primary focus is on calcium signaling. The lab employs genetic, cell, bioinformatic, and biochemical approaches, using Arabidopsis and yeast as model systems. Specific aims are focused on questions of enzyme structure and function for members of the following three gene families. Calcium Dependent Protein Kinases (CDPKs). CDPKs have a unique structure defined by the presence of a calmodulin-like regulatory domain fused to the C-terminal end of the kinase. They are only found in plants and some protist, including the human parasite Plasmodium, the causative agent of malaria. Cyclic Nucleotide Gated Channels (CNGCs). These ion channels have been implicated in calcium signaling and are regulated by both cyclic nucleotides and calmodulin. P-type ATPase Ion Pumps. These ion pumps are used to transport across membranes a wide variety of ions, including H+, Ca2+, Na+, and heavy metals. They are involved in ion homeostasis, nutrient acquisition from the soil, toxic ion efflux, and signal transduction.