Ephrin Type A Receptor 9 (EPHA9)

Protein tyrosine kinase (TK) receptors are known to play crucial roles in various aspects of normal development and in tumorigenesis. One of the receptor TK genes appeared to be novel, and thus the full-length DNA complementary to RNA (cDNA) sequence was retrieved by the rapid cloning of cDNA ends method. Sequence analysis of this cDNA indicated that it encoded a novel TK receptor of the Eph family. TNorthern blot hybridizations indicated that ephA9 RNA transcripts were present in the kidney, lung, testis, and thymus but not in the spleen, brain, or liver. Expression of a fusion protein containing the intracellular domain of EphA9 in bacterial cells showed that this domain had TK enzymatic activity. The EphA9 species produced in Cos-1 cells transfected with an expression vector were tyrosine-phosphorylated. EphA9 plays its biological role(s) in various organs of chickens as an active TK.