||Fig. 1. Xenopus laevis frizzled 7 (Xfz7) sequence and expression in embryonic development. (A) Deduced Xfz7 protein sequence. The amino-terminal signal sequence is shown in purple, conserved cysteines are in bold, and the putative PDZ-binding motif is in red. Consensus N-linked glycosylation sites are in green, and the putative transmembrane domains are underlined. (B) Estimated evolutionary relationship of Xfz7 with other known frizzled proteins. Proteins displaying the greatest
sequence similarity cluster together. Using this analysis, three highly distinctive structural groups were identiﬁed. (C) Northern analysis of
Xfz7 expression. O, 2, 7, 10, 11, 18, 27 denote oocyte, and stages 2-27, respectively. D, V lanes contain RNA from dorsal and ventral halves of
stage 10+ embryos. Only a single 4.6 kb band is observed in all stages examined. (D,E,G,J) dorsal is up, (F,H-J) anterior is to the left. (D-J) Xfz7
distribution as determined by in situ hybridization. The scale bars correspond to 1 mm. (D,E) Animal and vegetal views of stage 11 embryo. Note the preferential dorsal enrichment of Xfz7 transcripts at this stage of development that correlates with the northern data.
(F,G) Dorsal and rostral views of stage 14 embryo. Staining is apparent at, but not limited to, anterior neural folds. (H) Dorsal view of stage 17 embryo. Expression is apparent at neural folds and more weakly in the somites. (I) Dorsal view of stage 20 embryo. Xfz7 RNA is found in
the neural folds and forming pharyngeal arches. (J) Lateral view of stage 27 embryo. Black arrowhead marks the eye, white arrowhead labels the pharyngeal arches, and black arrow is the pronephros.