Mouse Tec is a non-receptor type protein-tyrosine kinase and is highly expressed 
in many hematopoietic cell lines. To investigate the roles of the Tec kinase in 
the human hematopoietic system, we isolated cDNAs encoding the human Tec kinase. 
The human tec cDNAs can encode a peptide of 631 amino acid residues with a 
calculated molecular mass of 73,624. The predicted human Tec protein is highly 
homologous to those of the members of the Tec family including mouse Tec type IV 
(94% homology), mouse Tsk/Itk (60%), and human Btk (57%). The homology between 
human Tec and other members of the Tec family can be observed not only in the 
Src homology 3 (SH3), SH2, and kinase domains, but also in the N-terminal unique 
domain. Northern blot analysis demonstrated that the major transcripts of tec 
could be detected at 2.6 kb and 3.6 kb in a wide range of human hematopoietic 
cell lines including myeloid, B-, and T-cell lineages. Interestingly, high 
expression of the tec gene could be detected in all of the three patients 
examined with myelodysplastic syndrome. The human tec gene was mapped by 
fluorescence in situ hybridization (FISH) to chromosome 4p12.