Molecular cloning, differential expression, and chromosomal localization of human frizzled-1, frizzled-2, and frizzled-7.

cDNAs for three human Wnt receptors, Frizzled-1 (FZD1), Frizzled-2 (FZD2), and Frizzled-7 (FZD7), have now been cloned and characterized. The FZD1, FZD2, and FZD7 genes encode the 647-, 565-, and 574-amino-acid proteins, respectively. FZD1, FZD2, and FZD7 share a common structure consisting of seven transmembrane domains, a cysteine-rich domain in the N-terminal extracellular region, and the C-terminal Ser/Thr-Xxx-Val motif. Relatively large amounts of FZD 1 mRNA, 4.5 kb in size, were detected in adult heart, placenta, lung, kidney, pancreas, prostate, and ovary and in fetal lung and kidney. FZD2 mRNAs 4.0 and 2.4 kb in size were detected in adult heart, fetal brain, lung, and kidney. The level of FZD7 mRNAs 5.0 and 4.0 kb in size was high in adult skeletal muscle and fetal kidney, followed by fetal lung, adult heart, brain, and placenta. The FZD1 and FZD7 genes have been mapped to human chromosome 7q21 and 2q33, respectively.