PKD variants and activity. A) Schematic representation of Drosophila wild type and mutant UAS-PKD variants, PKD-WT, PKD-kd, PKD-SE, dsPKD and human PKD variants, hPKD2 and hPKD3. Apart from dsPKD, all proteins were expressed as GFP fusion proteins. PKD contains a regulatory domain and a kinase domain. The characteristic features include: C1, C2, Zink-fingers 1 and 2; A, acidic domain; PH, pleckstrin homology domain; KD, kinase domain. In addition, hPKD2 contains a proline rich domain (P) at the N-terminal end and a serine rich region between the two zinc fingers (purple box). Two serine residues in the kinase domain (Ser689, Ser702) are thought to be phosphorylated upon activation of PKD. They were both mutated to glutamic acid in PKD-SE. hPKD2 contains a further possible auto-phosphorylation target within the C-terminus. The presumptive ATP binding site, lysine at the beginning of the kinase domain (K572), is highlighted. It was altered to tryptophane in PKD-kd. Numbers refer to codons; they are according to  for hPKDs and  for Drosophila PKD. B-E) Fidelity and level of expression for the different variants was analyzed in vivo by help of the GFP-tag. Different Gal4-driver lines were used to address tissue specificity of GFP-expression. The examples show specific GFP-expression in the posterior compartment of a wing imaginal disc (right half) as can be achieved by using the en-Gal4 driver line. For better visualization, discs are outlined with dotted lines. The antero-posterior (yellow line) and the dorso-ventral borders (purple line) are indicated in B). Shown are B) wild type PKD (en-Gal4/PKD-WT10-1), C) PKD-SE (en-Gal4/PKD-SE112-6), D) PKD-kd (en-Gal4/PKD-kd102-1) and E) hPKD3 (en-Gal4/hPKD3X-1). Scale bar, 100 μm.
Maier et al. BMC Developmental Biology 2007 7:74 doi:10.1186/1471-213X-7-74