The human ryk cDNA sequence predicts a protein containing two putative transmembrane segments and a tyrosine kinase catalytic domain.

The human ryk tyrosine kinase cDNA was originally identified as a PCR-amplified cDNA fragment (JTK5) from K562 leukemia cells and found to represent a ubiquitously expressed gene (Partanen et al., 1990). The open reading frame of human ryk, reported here, encodes a novel type of putative tyrosine kinase of 607 amino acid residues, having two potential transmembrane domains and homology to receptor tyrosine kinases, such as met (HGF/SF-R) and IGF-1R, in its catalytic domain. The gene maps to human chromosome 3q11-25. Expression of the 3.4 kb ryk mRNA was found in all human adult tissues examined.