Receptor tyrosine kinase

Receptor tyrosine kinase (RTK) is a high-affinity cell surface receptor for many polypeptide growth factors, cytokines, and hormones. Of the 90 unique tyrosine kinase genes identified in the human genome, 58 encode receptor tyrosine kinase proteins.

Structure

RTKs are single-pass transmembrane proteins. They share a common structural design with a ligand-binding extracellular domain, a single transmembrane helix, and an intracellular region that contains a protein tyrosine kinase domain flanked by regulatory elements.

Function

RTKs play a critical role in cellular communication, controlling cell growth, differentiation, metabolism, and migration. They are key regulators of normal cellular processes but can also promote cancer development and progression if mutated or overexpressed.

Classification

RTKs are classified into 20 subfamilies based on their structural characteristics and sequence homology. These include the EGFR (epidermal growth factor receptor) family, the Insulin receptor family, and the VEGFR (vascular endothelial growth factor receptor) family, among others.

Role in Disease

Dysregulation of RTK signaling pathways plays a critical role in the development of cancer. Mutations in RTK genes can lead to overexpression of the receptor, or cause the receptor to be constantly activated, even in the absence of growth factors.

Therapeutic Target

Because of their critical role in cancer, RTKs have become important targets for cancer therapy. Several drugs that target RTKs have been approved for use in cancer treatment, including Gefitinib for non-small cell lung cancer and Trastuzumab for breast cancer.