MOLECULAR-CLONING OF A NOVEL RECEPTOR TYROSINE KINASE, TIF, HIGHLY EXPRESSED IN HUMAN OVARY AND TESTIS

Using a combination of polymerase chain reaction and conventional cDNA library screening approaches, we have cloned and characterized a putative receptor tyrosine kinase termed tif. The extracellular domain of tif has an immunoglobulin-like loop and a fibronectin type III structure. The intracellular domain contains a tyrosine kinase domain. Compared with ryk, a ubiquitously expressed receptor tyrosine kinase, tif expression is tissue-specific with human ovary and testis containing the highest amount of tif mRNA. Many other tested human tissues such as heart, liver, pancreas and thymus do not contain detectable levels of tif mRNA. The molecular cloning and characterization of tif cDNA will facilitate the identification of a potential ligand(s) for the putative receptor and the study of its biological role.