Frizzled-1 (FZD1), FZD2, FZD3, FZD4, FZD5, FZD6, FZD7, FZD8, FZD9 and FZD10 are seven-transmembrane-type WNT receptors with extracellular Frizzled (Fz) domain. ROR1, ROR2 and MUSK are receptor-type tyrosine kinases with extracellular Fz domain, while MFRP is type II transmembrane protein with extracellular Fz domain. ROR1, ROR2, MUSK and MFRP are predicted to transduce or regulate WNT signaling. Here, we identified and characterized rat Ror1 and Ror2 genes by using bioinformatics. Rat Ror1 gene was located within AC108320.4, AC098031.5 and AC129856.4 genome sequences, while rat Ror2 gene was located within AC139870.3 and AC123431.4 genome sequences. Exon-intron structure was conserved between rat Ror1 and Ror2 genes, consisting of nine exons. Rat Ror1 mRNA was expressed in fetal ventricle, while rat Ror2 mRNA was expressed in cerebral cortex, hypothalamus, dorsolateral prostate, and chondrosarcoma. Rat Ror1 (937 aa) and Ror2 (943 aa) showed 56.5% total-amino-acid identity. Rat Ror1 and Ror2 were type I transmembrane proteins with extracellular Immunoglobulin-like (Ig), Fz, Kringle (KR) domains, and cytoplasmic Juxta-membrane (JM), Tyrosine kinase (TK), and Ror homology C-terminal (RORHC) domains. Casein kinase Iε-binding RORHC domain was conserved among vertebrate Ror1 and Ror2 homologs, but not in Drosophila Ror. Thr 582 within TK domain was conserved among mammalian Ror family members, and was predicted as Casein kinase I phosphorylation site. This is the first report on rat Ror1 and Ror2 genes as well as on molecular evolution of Ror1 and Ror2 homologs.

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