Human Protein Tyrosine Kinase 6 (PTK6) Protein

Background

Protein Tyrosine Kinase 6 (PTK6), also known as BRK (Breast Tumor Kinase), is a non-receptor tyrosine kinase that is predominantly expressed in epithelial tissues and involved in regulating cell growth, differentiation, and stress responses. PTK6 is structurally similar to Src family kinases but functions independently of membrane localization. It contains an SH3 domain, SH2 domain, and a tyrosine kinase domain. PTK6 is localized in both the nucleus and cytoplasm, where it regulates distinct signaling pathways. In normal epithelial cells, PTK6 regulates differentiation and maintenance of tissue integrity. However, in cancers, particularly breast, colorectal, and prostate cancer, PTK6 is frequently upregulated and promotes cell proliferation, migration, and survival. PTK6 enhances signaling through pathways such as STAT3, AKT, and ERK1/2, contributing to tumor progression. Interestingly, PTK6 can also act as a tumor suppressor under certain conditions by promoting cell differentiation. Beyond cancer, PTK6 is involved in stress responses, including DNA damage repair and oxidative stress resistance. Its dual role in cell survival and differentiation makes PTK6 a potential therapeutic target in oncology.