Human ltk: gene structure and preferential expression in human leukemic cells.

We have isolated the human homolog (hltk) of the murine tyrosine kinase gene ltk from a K-562 human leukemia cDNA library. The deduced protein sequence of hltk is 17 amino acids longer in the juxtamembrane domain and 28 amino acids shorter in the carboxy terminus than that of murine ltk. The partially identical splicing points of hltk to those of c-ros showed a close genetic linkage between the two. In Northern blot analysis of 35 human malignancies, hltk is preferentially expressed in leukemias (10 out of 18 cases) with no cell lineage specificity, but none of 17 nonleukemic neoplasms expressed hltk gene.