The proto-oncogene of v-eyk (v-ryk) is a novel receptor-type protein tyrosine kinase with extracellular Ig/GN-III domains.

v-ryk is the oncogene in the avian acute oncogenic retrovirus RPL30, its cellular counterpart, c-ryk, is described in this report. To avoid the confusion caused by another gene with the same name, we renamed v-ryk to be v-eyk, thereby changing the proto-oncogene's name to c-eyk. c-eyk is expressed highly in chicken spleen and moderately in many other tissues including embryonic tissues. Its cDNA is 3061 base pairs encoding a receptor-type protein tyrosine kinase (PTK) of 974 amino acids. Compared to c-Eyk, v-Eyk is a truncated PTK lacking the extracellular and transmembrane regions of c-Eyk in addition to two amino acid changes. c-Eyk has two C2-type Ig domains and two FN-III domains in its extracellular region, forming a new subfamily of receptor-type PTK together with UFO/Axl/Ark. As suggested by Ig/Fn-III domains in many cell adhesion molecules, this subfamily of PTK may mediate cell-cell interaction.