Isolation of a novel receptor tyrosine kinase cDNA expressed by developing erythroid progenitors

Activation of distinct receptor tyrosine kinases (RTK), such as the products of the c-fms and c-kit proto-oncogenes, profoundly affects hematopoietic development. We have isolated a novel RTK cDNA, called met-related kinase (MRK), which is expressed on early erythroid progenitors. MRK is also expressed in many hematopoietic cell lines, and is not lineage restricted. Several regions within the catalytic domain of MRK have amino acid similarity to the c-met proto-oncogene and v-sea oncogene. Specific polyclonal anti-MRK antisera detects an 84- Kd polypeptide in COS cells transfected with an expression vector containing the MRK cDNA. Further studies of this novel RTK will provide potential insight into its role during hematopoiesis.