A NOVEL PROTEIN-KINASE GENE FAMILY IN GIARDIA-DUODENALIS

Two protein kinase (PK) genes, gPK1 and gPK2, were cloned from the gen ome of the ancient protozoan parasite, Giardia duodenalis (Gd). Both g PK genes and their products are highly homologous (85% and 77% identic al, respectively). gPK1 and gPK2 contain all the motifs characteristic of PK, but they are not highly homologous to other PK and therefore b elong to a novel PK gene family. Northern blot analysis showed that th e gPK genes are expressed in vivo. Southern blot analysis indicated th at there are other homologous PK genes in the Gd genome. gPK1 and gPK2 are the first full-length PK genes cloned from this primitive eukaryo te. The unique amino acid (aa) sequences of gPK1 and gPK2 suggest that they are involved in unique biological functions in Gd.