The presence of a Src homology 2 (SH2) domain sequence similarity in the sequence of Janus kinases (Jaks) has been discussed since the first descriptions of these enzymes. We performed an in depth study to determine the function of the Jak1 SH2 domain. We investigated the functionality of the Jak1 SH2 domain by stably reconstituting Jak1-defective human fibrosarcoma cells U4C with endogenous amounts of Jak1 in which the crucial arginine residue Arg466 within the SH2 domain has been replaced by lysine. This mutant still binds to the receptor subunits gp130 and OSMR. Moreover, the SH2 R466K mutation does not affect the subcellular distribution of Jak1 as assessed by cell fractionation and confocal microscopy of cells expressing endogenous levels of non-tagged or a yellow fluorescent protein (YFP)-tagged Jak1-R466K, respectively. Likewise, the signaling capacity of Jak1 was not affected by this point mutation. However, we found that the SH2 domain is structurally important for cytokine receptor binding and surface expression of the OSMR.
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http://dx.doi.org/10.1074/jbc.M500822200 | DOI Listing |
Mol Divers
January 2025
Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal, 576104, India.
SH2 (Src Homology 2) domains play a crucial role in phosphotyrosine-mediated signaling and have emerged as promising drug targets, particularly in cancer therapy. STAT3 (Signal Transducer and Activator of Transcription 3), which contains an SH2 domain, plays a pivotal role in cancer progression and immune evasion because it facilitates the dimerization of STAT3, which is essential for their activation and subsequent nuclear translocation. SH2 domain-mediated STAT3 inhibition disrupts this binding, reduces phosphorylation of STAT3, and impairs dimerization.
View Article and Find Full Text PDFShort linear peptide motifs play important roles in cell signaling. They can act as modification sites for enzymes and as recognition sites for peptide binding domains. SH2 domains bind specifically to tyrosine-phosphorylated proteins, with the affinity of the interaction depending strongly on the flanking sequence.
View Article and Find Full Text PDFLeuk Lymphoma
January 2025
National Clinical Research Center for Hematologic Diseases, Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China.
Alterations in the RAS pathway underscore the pathogenic complexity of acute myeloid leukemia (AML), yet the full spectrum, including , , , , and , remains to be fully elucidated. In this retrospective study of 735 adult AML patients, the incidence of RAS pathway alterations was 32.4%, each with distinct clinical characteristics.
View Article and Find Full Text PDFOral Dis
December 2024
Department of Oral and Maxillofacial Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Objectives: The effects of systemic inflammation on the temporomandibular joint (TMJ) are poorly understood. This study aimed to establish a mouse model to study the effects of systemic inflammation on the TMJ.
Materials And Methods: SKG mice, a BALB/c strain with spontaneous onset of rheumatoid arthritis-like symptoms due to a spontaneous point mutation (W163C) in the gene encoding the SH2 domain of ZAP-70, were treated with zymosan (β-1,3-glucan).
Protein Sci
January 2025
Department of Physics, University of Toronto, Toronto, Ontario, Canada.
The point mutation N642H of the signal transducer and activator of transcription 5B (STAT5B) protein is associated with aggressive and drug-resistant forms of leukemia. This mutation is thought to promote cancer due to hyperactivation of STAT5B caused by increased stability of the active, parallel dimer state. However, the molecular mechanism leading to this stabilization is not well understood as there is currently no structure of the parallel dimer.
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