TRANSFERASE, STRUCTURAL GENOMICS, PROTIST PARASITE, CRYPTOSPORIDIUM PARVUM, CDPK, CALCIUM, ZINC FINGER, ATP-BINDING, KINASE, NUCLEOTIDE-BINDING, SERINE/THREONINE-PROTEIN KINASE, STRUCTURAL GENOMICS CONSORTIUM, SGC 3HKO CRYSTAL STRUCTURE OF A CDPK KINASE DOMAIN FROM CRYPTOSPORIDIUM PARVUM, CGD7_40