Tyrosine-protein kinase ABL1 also known as ABL1 is a protein that, in humans, is encoded by the ABL1 gene (previous symbol ABL) located on chromosome 9. [5] c-Abl is sometimes used to refer to the version of the gene found within the mammalian genome, while v-Abl refers to the viral gene, which was initially isolated from the Abelson murine leukemia virus. [6]
The ABL1 proto-oncogene encodes a cytoplasmic and nuclear protein tyrosine kinase that has been implicated in processes of cell differentiation, cell division, cell adhesion, and stress response such as DNA repair. [7] [8] [9] [10] Activity of ABL1 protein is negatively regulated by its SH3 domain, and deletion of the SH3 domain turns ABL1 into an oncogene. The t(9;22) translocation results in the head-to-tail fusion of the BCR and ABL1 genes, leading to a fusion gene present in many cases of chronic myelogenous leukemia. The DNA-binding activity of the ubiquitously expressed ABL1 tyrosine kinase is regulated by CDC2-mediated phosphorylation, suggesting a cell cycle function for ABL1. The ABL1 gene is expressed as either a 6- or a 7-kb mRNA transcript, with alternatively spliced first exons spliced to the common exons 2–11. [11]
Mutations in the ABL1 gene are associated with chronic myelogenous leukemia (CML). In CML, the gene is activated by being translocated within the BCR (breakpoint cluster region) gene on chromosome 22. This new fusion gene, BCR-ABL, encodes an unregulated, cytoplasm-targeted tyrosine kinase that allows the cells to proliferate without being regulated by cytokines. This, in turn, allows the cell to become cancerous.
This gene is a partner in a fusion gene with the BCR gene in the Philadelphia chromosome, a characteristic abnormality in chronic myelogenous leukemia (CML) and rarely in some other leukemia forms. The BCR-ABL transcript encodes a tyrosine kinase, which activates mediators of the cell cycle regulation system, leading to a clonal myeloproliferative disorder. The BCR-ABL protein can be inhibited by various small molecules. One such inhibitor is imatinib mesylate, which occupies the tyrosine kinase domain and inhibits BCR-ABL's influence on the cell cycle. Second generation BCR-ABL tyrosine-kinase inhibitors are also under development to inhibit BCR-ABL mutants resistant to imatinib. [12]
ABL gene has been shown to interact with:
There is some evidence that the expression of Abl is regulated by the microRNA miR-203. [61]
The Philadelphia chromosome or Philadelphia translocation (Ph) is a specific genetic abnormality in chromosome 22 of leukemia cancer cells. This chromosome is defective and unusually short because of reciprocal translocation, t(9;22)(q34;q11), of genetic material between chromosome 9 and chromosome 22, and contains a fusion gene called BCR-ABL1. This gene is the ABL1 gene of chromosome 9 juxtaposed onto the breakpoint cluster region BCR gene of chromosome 22, coding for a hybrid protein: a tyrosine kinase signaling protein that is "always on", causing the cell to divide uncontrollably by interrupting the stability of the genome and impairing various signaling pathways governing the cell cycle.
Growth factor receptor-bound protein 2, also known as Grb2, is an adaptor protein involved in signal transduction/cell communication. In humans, the GRB2 protein is encoded by the GRB2 gene.
The breakpoint cluster region protein (BCR) also known as renal carcinoma antigen NY-REN-26 is a protein that in humans is encoded by the BCR gene. BCR is one of the two genes in the BCR-ABL fusion protein, which is associated with the Philadelphia chromosome. Two transcript variants encoding different isoforms have been found for this gene.
Adapter molecule crk also known as proto-oncogene c-Crk is a protein that in humans is encoded by the CRK gene.
Tyrosine-protein phosphatase non-receptor type 6, also known as Src homology region 2 domain-containing phosphatase-1 (SHP-1), is an enzyme that in humans is encoded by the PTPN6 gene.
Cbl is a mammalian gene family. CBL gene, a part of the Cbl family, encodes the protein CBL which is an E3 ubiquitin-protein ligase involved in cell signalling and protein ubiquitination. Mutations to this gene have been implicated in a number of human cancers, particularly acute myeloid leukaemia.
Tyrosine-protein kinase HCK is an enzyme that in humans is encoded by the HCK gene.
RAS p21 protein activator 1 or RasGAP, also known as RASA1, is a 120-kDa cytosolic human protein that provides two principal activities:
Crk-like protein is a protein that in humans is encoded by the CRKL gene.
Docking protein 1 is a protein that in humans is encoded by the DOK1 gene.
CBL-B is an E3 ubiquitin-protein ligase that in humans is encoded by the CBLB gene. CBLB is a member of the CBL gene family.
Proto-oncogene vav is a protein that in humans is encoded by the VAV1 gene.
Cytoplasmic protein NCK1 is a protein that in humans is encoded by the NCK1 gene.
Tyrosine-protein phosphatase non-receptor type 12 is an enzyme that in humans is encoded by the PTPN12 gene.
Tyrosine-protein kinase ABL2 also known as Abelson-related gene (Arg) is an enzyme that in humans is encoded by the ABL2 gene.
Megakaryocyte-associated tyrosine-protein kinase is an enzyme that in humans is encoded by the MATK gene.
Cytoplasmic tyrosine-protein kinase BMX is an enzyme that in humans is encoded by the BMX gene.
Docking protein 2 is a protein that in humans is encoded by the DOK2 gene.
Abl interactor 2 also known as Abelson interactor 2 (Abi-2) is a protein that in humans is encoded by the ABI2 gene.
A non-receptor tyrosine kinase (nRTK) is a cytosolic enzyme that is responsible for catalysing the transfer of a phosphate group from a nucleoside triphosphate donor, such as ATP, to tyrosine residues in proteins. Non-receptor tyrosine kinases are a subgroup of protein family tyrosine kinases, enzymes that can transfer the phosphate group from ATP to a tyrosine residue of a protein (phosphorylation). These enzymes regulate many cellular functions by switching on or switching off other enzymes in a cell.
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