RTK class X

In humans, leukocyte receptor tyrosine kinase is a member of ALK / LTK receptor family (RTK) receptor tyrosine kinase ligand-unknown, an enzyme encoded by the protein gene.The LTK this gene. I related to the insulin receptor family of RTK closely. It is important to control the various routes leading tyrosine phosphorylation of a particular protein, and cell proliferation and differentiation. Selective spliced ​​transcript variants encoding two different isoforms described for this gene.LTK, that it interacts with PIK3R1 and IRS-1, SHC is shown.

RTK class X


Leukocyte tyrosine kinase (LTK) is a receptor tyrosine kinase that belongs to the insulin receptor superfamily, pre-B lymphocytes and is mainly expressed in neuronal tissues. Recently, we as a uniform activation of the pathway of Ras substrate and the two main, IRS-1 and used LTK SHC is present downstream of the signal transduction pathways unidentified IRS-1 only IRS-1 and also to its anti-apoptotic activity was revealed that the inhibition suggests, apoptosis of hematopoietic cells. In this study, wortmannin, phosphatidylinositol 3 ‘(PI3) we – specific inhibitor of the kinase was found that the survival effect of LTK is deleted. -CBL Because LTK and PI3-kinase and IRS-1 in, and are known to be phosphorylated by the second candidate binding LTK, but we, related to tyrosine 753 of LTK with direct P85 subunit of PI3 kinase Located on the YxxM motif consensus amino acid sequence of the SH2 domain binding of the P85 found that you have, but have failed to connect to the C-CBL or IRS-1. Suggests that PI3 kinase is required for the survival effect of LTK, Ba/F3 cells expressing the receptor carrying a mutation in stable EGF-LTK chimeric receptor tyrosine 753, even in the presence of EGF I fell in apoptotic death.

We isolated (hltk) human homolog of the mouse tyrosine kinase gene LTK K-562 human leukemia cDNA library. Protein sequence deduced is a 17 amino acid long hltk is 28 amino acids shorter carboxy terminus than that of the mouse LTK and juxtamembrane domain. I showed a genetic relationship between both of the same points to close and partially of hltk C-SSR in splicing. In Northern blot analysis of 35 human malignant tumor, is hltk, specificity, the expression of the gene one of the 17 nonleukemic tumor hltk is without expressed in leukemia (18 cases of 10) cell line preferably.

It is important to control the various routes leading tyrosine phosphorylation of a particular protein, the differentiation1 and cell proliferation. Protein tyrosine kinase that has been described so far, is one of the cytoplasmic protein or protein DOMAIN2-7 has a transmembrane extracellular ligand related to oncogene8-10 V-SRC. Most of these proteins, like the various cells and tissues, are expressed in tissues specific1 some. In previous studies, protein lymphokines, of insulin receptor13 – that some cells to mediate the survival of hematopoietic cells by the action of those for transport 11, 12 glucose regulation by the activity of tyrosine kinase has been shown. We examined the possibility of insulin receptor, and genes that are expressed in hematopoietic cells. Were isolated (white blood cell tyrosine kinase), use of insulin receptor-related avian sarcoma cancer genes probe14 V like the ROS, have characterized a new gene DNA complementary, the LTK we. Associated with several genes that are expressed in leukocytes, primarily tyrosine kinase receptor family, insulin receptor, and having structural characteristics unique LTK genes: transmembrane proteins lacking the extracellular domain obviously it I encoding. Proposed one protein LTK 2 has a characteristic to identify antibodies thymus of mice, indicating that they are integral membrane proteins. These characteristics, LTK, indicating that it may be a signal transduction pathway subunits of one or more hematopoietic receptors.

The structure of this protein tyrosine kinase LTK is suggested that in order to short the only, or almost non-existent, it is unique, including a transmembrane domain, extracellular domain between the tyrosine kinase prior to analysis of the cDNA are. Moreover, they said translation initiation codon, and there is a possibility that CTG occurs in particular. We sequenced the DNA sequence of the full-length human LTK deduced already cloned We new information is included as compared with the cDNA that were previously identified. Extracellular domain of 347 amino acids ATG translation start codon, a secretion signal sequence, an intracellular kinase transmembrane domains: The LTK, this cDNA encodes a protein comprising all functions of receptor tyrosine kinases typically. The ribonuclease protection analysis, DNA was cloned We show that it represents the most common type of mature mRNA LTK. a protein of 100 kDa LTK according to an estimated ATG translation initiation codon in vitro transcription and translation of the yield of cDNA. Also, COS-1 cells transfected with the cDNA in LTK produced a protein kinase activity has the same size as the glycosylation at in vitro. These data are gene products, LTK, indicating that it may function as cell surface receptors for growth factors unidentified.

Leukocyte tyrosine kinase (LTK) is a receptor tyrosine kinase belonging to the family of insulin receptor is expressed in the brain and pre-B cells, mainly. Displays as two substrate main SHC In this study, we are using insulin receptor substrate 1 of LTK the (IRS-1), have the NPXY two reasons for them individually, film of IRS-1 862 another NPXY motif carboxy-terminal domain of tyrosine tyrosine SHC 485 and, in the vicinity domain NPXY motif. By using the Ba/F3 cells expressing epidermal growth factor receptor LTK chimeric receptor containing a mutation in the NPXY site, contributing to the generation of mitogenic signals activation and tyrosine, Las, the NPXY motif We have two LTK 485 indicate that while sends a signal to cell survival. These data, IRS-1, indicating that have anti-apoptotic functions of LTK signaling least. Furthermore, the survival signaling pathway LTK, our data show that different from the P70 (S6) kinase pathways and path RAS. Our results provide useful insight into the understanding of the various roles of IRS-1 and SHC in the signal transduction system of the family of insulin receptor, anti-apoptotic function of IRS-1, the interleukins and IGF-1, 4, it may explain the survival effect of insulin.