TXK, a novel human tyrosine kinase expressed in T cells shares sequence identity with Tec family kinases and maps to 4p12.
A gene for a novel, putative cytoplasmic tyrosine kinase, TXK has been isolated from a human peripheral blood cDNA library. The complete nucleotide sequence of the cDNA indicates that it is related most closely to EMT, a tyrosine kinase of T cells and to the B-cell tyrosine kinase Btk, which is mutated in X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency disease (XID) in mouse. TXK, like BTK, is a member of the Tec sub-family of Src-type (non-receptor) tyrosine kinases. Like similar Tec sub-family members, and unlike the other Src kinases, TXK lacks both the N-terminal myristylation signal and the C-terminal regulatory tyrosine. TXK expression is detected primarily in T cells and some myeloid cell lines but not in a number of other cell types. TXK shares 60% amino acid homology with EMT and 57% with BTK over the SH3, SH2 (Src-homology) and catalytic domains but unlike BTK, EMT and tec, it lacks Gap 1 homology and steroid hormone receptor homology in the N-terminal region. Genomic clones containing TXK have been isolated and hybridize to chromosome position 4p12.
Department of Pediatrics, University of South Florida, All Children's Hospital, St Petersburg 33701.
R N
RN
Haire
Y
Y
Ohta
J E
JE
Lewis
S M
SM
Fu
P
P
Kroisel
G W
GW
Litman
D000595:Amino Acid Sequence; D001483:Base Sequence; D001853:Bone Marrow / Q000201:enzymology; D002478:Cells, Cultured; D002874:Chromosome Mapping; D002894:Chromosomes, Human, Pair 4; D017931:DNA Primers; D015723:Gene Library; D006801:Humans; D007621:Karyotyping; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000235:genetics*; D012016:Reference Values; D017386:Sequence Homology, Amino Acid; D013601:T-Lymphocytes / Q000201:enzymology*
D017931:DNA Primers; D015345:Oligonucleotide Probes; C089848:Tec protein-tyrosine kinase; D011505:Protein-Tyrosine Kinases