|Detection of LRIG1 in LNCaP Human Cell Line by Flow Cytometry. LNCaP human prostate cancer cell line was stained with Mouse Anti-Human LRIG1 PE‑conjugated Monoclonal Antibody (Catalog # FAB7498P, filled histogram) or isotype control antibody (Catalog # IC0041P, open histogram). View our protocol for Staining Membrane-associated Proteins.|
LRIG1 (Leucine-rich Repeats and Ig-like domains-1), also known as LIG-1, is an approximately 134-145 kDa type I transmembrane glycoprotein that belongs to the LRIG gene family. It is widely expressed and appears on the surface of prostatic epithelium, endothelial cells, vascular and visceral smooth muscle cells, mammary epithelium, cardiac muscle cells, keratinocytes and neurons. LRIG1 is believed to negatively regulate the ErbB family of receptors. In particular, and in a ligand-independent manner, LRIG1 complexes with all four ErbBs, promoting their ubiquitination and decreasing their number. Alternatively, LRIG1 is suggested to bind to the ErbBs, preventing their dimerization and signal transduction. Mature human LRIG1 is 1059 amino acids (aa) in length. It contains a large 760 amino acid (aa) extracellular domain (ECD) (aa 35-794) plus a 278 aa cytoplasmic region. The ECD contains 17 LRRs (aa 35‑491) and three C2-type Ig-like domains (aa 495-780). These two domain types are each sufficient for EGFR binding. There are two potential alternative splice forms. One contains a 27 aa insertion after Gly874, while another shows a 24 aa insertion after Lys387 coupled to a Gln substitution for aa 644-691. The LRIG1 ECD undergoes proteolysis, generating 100-110 and 55-60 kDa soluble fragments. Over aa 35‑779, human LRIG1 shares 90% aa sequence identity with mouse LRIG1.