Identification of four murine cDNAs encoding putative protein kinases from primitive embryonic stem cells differentiated in vitro.

Protein kinases transduce signals from extracellular ligands in the hematopoietic and other systems through direct phosphorylation of tyrosine, serine, or threonine residues. Little is known about the ligands and receptors that are important in the earliest stages of development--i.e., stem cell self-renewal and lineage commitment. We have made use of the lineage differentiation potential of the murine embryonic stem cell system to clone partial cDNAs encoding four putative protein kinases. Three of the four genes contain the highly conserved residues Asp-Phe-Gly in domain VII of the protein kinase family. These genes are candidates for receptors or downstream effectors of cytokines that regulate self-renewal and lineage commitment in embryogenesis.