Leukocyte Tyrosine Kinase (LTK)

LTK is a member of the ros/insulin receptor family of tyrosine kinases. Tyrosine-specific phosphorylation of proteins is a key to the control of diverse pathways leading to cell growth and differentiation. Two alternatively spliced transcript variants encoding different isoforms have been described for this gene.These cDNAs predicted a truncated receptor protein that lacks the tyrosine kinase domain and a soluble receptor protein that has neither a transmembrane nor a tyrosine kinase domain. A cDNA clone containing the complete open reading frame demonstrated that the extracellular domain of the receptor protein is larger than previously predicted. Thus, the LTK gene produces not only the putative receptor tyrosine kinase for an unknown ligand but also multiple protein products that may have different functions.