JAK1编码蛋白是Janus激酶1（JAK1），其是JAK蛋白酪氨酸激酶家族中普遍表达的成员，其是一种细胞内激酶。JAK1与细胞因子受体形成复合物以启动细胞因子介导的信号传导。在细胞因子活化后，JAK1形成寡聚二聚体，其使细胞因子受体的细胞质区域内的酪氨酸残基磷酸化，导致下游靶标如STAT1-6的募集和活化。然后STAT蛋白易位至细胞核并充当转录因子，介导几种细胞功能，包括增殖，分化和抗原呈递。在急性淋巴细胞白血病和其他血液系统恶性肿瘤中已经检测到JAK1中的几种激活突变；另外，在妇科肿瘤中也有报道检测到JAK1功能丧失的截短突变。

JAK1 gene encodes Janus kinase 1 (JAK1), a ubiquitously expressed member of the JAK family of protein tyrosine kinases. JAK1 forms a complex with cytokine receptors to initiate cytokine-mediated signaling. Upon cytokine activation, JAK1 forms oligodimers which phosphorylate tyrosine residues within the cytoplasmic region of the cytokine receptors, leading to recruitment and activation of downstream targets such as STAT1-6. The STAT proteins then translocate to the nucleus and act as transcription factors, mediating several cellular functions including proliferation, differentiation and antigen presentation. Several activating mutations in JAK1 have been detected in acute lymphoblastic leukemia and other hematological malignancies. However, truncating mutations leading to loss-of-function of JAK1 have been frequently reported in gynecologic tumors and other cancers with microsatellite instability.

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