Novel members of the eph receptor tyrosine kinase subfamily expressed during Xenopus development.

Three cDNAs encoding receptor tyrosine kinases (RTKs) of the eph-subfamily have been identified based on their homology to Pagliaccio (Winning and Sargent, 1994, Mech. Dev. 46:219-229). These have been named TCK, Xelk (Xenopus homologue of elk), and PL7a (pag-like clone 7a). Each of these genes is expressed in a distinctive, tissue specific manner during early development. TCK is expressed in pre-somitic mesoderm, caudal somites, midbrain and cement gland. Xelk is expressed in the brain and spinal cord and in the first and fourth visceral arches. PL7a cDNA is expressed throughout the head and in the tip of the tail. All of the genes are represented in maternal mRNA, and are expressed in adult tissues. The Xelk cDNA encodes a protein which is 94% identical to rat elk and therefore is likely to represent the Xenopus homologue of this gene. TCK and PL7a are less related to previously identified eph-subfamily RTKs. The inability to unambiguously assign TCK and PL7a as Xenopus homologues of any previously identified eph RTK leads us to conclude that these cDNAs represent novel members of this family.