MOLECULAR-CLONING OF A NOVEL NONRECEPTOR TYROSINE KINASE, HYL (HEMATOPOIETIC CONSENSUS TYROSINE-LACKING KINASE)

We identified a novel non-receptor tyrosine kinase from a human megaka ryoblastic cell line, UT-7, by means of a PCR-based cloning method. Th e HYL gene contained a SH2 and SH3 domain and a tyrosine kinase cataly tic domain. The deduced amino acid sequence of the protein encoded by this gene was most homologous to CSK (c-src kinase). This gene and CSK shared some unique structural properties such as the absence of a myr istylation signal and phosphorylation sites of tyrosine residues corre sponding to tyrosines 416 and 527 of chicken p60c-src. Unlike CSK, the SH3 domain of HYL was unique since the ALYDY motif was absent. Northe rn blot analysis revealed a 2.2 kb transcript in various myeloid cell lines but not in adult tissues except for the brain and the lung, wher eas CSK mRNA was ubiquitously expressed. The expression of HYL was upr egulated when these myeloid cells were differentiated by induction wit h phorbol myristate acetate. We named this gene, hematopoietic consens us tyrosine-lacking kinase, HYL. The HYL gene was assigned to chromoso me 19 at band p13. It is suggested that HYL plays a significant role i n the signal transduction of hematopoietic cells.