WNT signals are transduced to the planar cell polarity (PCP) pathway or the β-catenin pathway. Drosophila Frizzled (Fz), Starry night (Stan), Van Gogh (Vang), Dishevelled (Dsh), Prickle (Pk), Diego (Dgo) and Nemo (Nmo) are implicated in the PCP signaling pathway. Choi and Benzer identified Drosophila Nmo in 1994, and Brott et al identified mouse Nemo-like kinase (Nlk) in 1998. Nlk positively regulates the PCP pathway, and negatively regulates the β-catenin pathway. Here, we identified and characterized rat Nlk gene, Nlk2 gene and Nlkp pseudogene by using bioinformatics. Nlk gene, consisting of 11 exons, was mapped to rat chromosome 10q25. Rat Nlk gene encoded 515-aa Nlk protein with the serine/threonine kinase domain, poly(His) tracts and poly(Ala) tract, which showed 100, 99.8, 97.1 and 89.5% total-amino-acid identity with mouse Nlk, human NLK, Xenopus nlk and zebrafish nlk, respectively. Rat Nlk2 gene and Nlkp pseudogene were mapped to rat chromosome 13p13 and 2q44, respectively. Nlk2 gene and Nlkp pseudogene, consisting of a single exon, were not evolutionarily conserved. Nlk2 gene and Nlkp pseudogene were predicted as retrotransposed Nlk homologs within the rat genome. Nlk2 gene encoded a 480-aa Nlk2 protein with partial deletion within the kinase domain, which was predicted as the dominant negative Nlk homolog. This is the first report on the Nlk gene and retrotransposed Nlk homologs within the rat genome.

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