Figure 2
Vrp1 domain organization and expression pattern. (A) Domain organization of Vrp1 proteins from Drosophila and mouse. Vrp1 has two WH2 domains (yellow boxes) and a WASP binding domain (pink box). Vrp1 is a very proline rich protein and the proline content is indicated in the Figure. (B-C) Vrp1 mRNA and protein expression patterns. (B) RNA in situ hybridization with Vrp1 anti-sense mRNA on wild type embryos. Vrp1 mRNA expression is detected in the visceral mesoderm at stage 11, dorsal view (arrow). (B'') At Stage 12 Vrp1 mRNA is visible in the somatic mesoderm (arrowhead) and visceral mesoderm (arrow), lateral view. (B''') Vrp1 mRNA expression in the somatic mesoderm of a stage 14 embryo (arrowhead), lateral view. (C) Vrp1 protein is detected with anti-Vrp1 antibodies in muscles of wild type embryos. (D) Rp298lacZ embryo, stained with anti-Vrp1 and anti-βGal antibodies. LacZ expression is detected in a FC cell specific pattern reflecting Duf/Kirre gene expression. No overlap between Vrp1 and β-gal expression is observed at early stages, indicating that Vrp1 is expressed only in the FCMs. (D') Close up of an rp298lacZ embryo, Vrp1 and β-gal expression. (D'') Close up of rp298lacZ embryo, β-gal expression alone. (E-G) Specificity of the Vrp1-antibodies is shown. (E) In wild type (WT) embryos Vrp1-antibodies detect Vrp1 protein in both SM and VM cells, indicated by arrowheads. (E') Nuclear Mef2 expression is detected in Vrp1 expressing cells (arrowheads). (F and G) No Vrp1 protein is detected in Vrp1f06715embryos (compare F with E) or in Vrp1f06715/Df(2R)ED3943 transheterozygous embryos (compare G with E) by the Vrp1 antibodies (arrowheads indicate absence of Vrp1 expression). (F' and G') Mef2 expression indicates the position of VM and SM cells (arrowheads indicate absence of Vrp1 expression in Mef2 expressing cells).