Recombinant Human NGL-1/LRRC4C Protein, CF

Human NGL-1 (Netrin-G1 ligand) is a 67 kDa (predicted for mature protein), type I transmembrane cell adhesion molecule that is a member of the NGL family of proteins (1 - 2). It is synthesized from a precursor that is 640 amino acids (aa) in length that contains a 44 aa signal sequence, a 483 aa extracellular region, a 21 aa transmembrane region, and a short cytoplasmic tail of 92 aa. The extracellular region of NGL-1 consists of nine leucine-rich repeats (LRRs) that are flanked by LRR N-terminal and LRR C-terminal domains, and followed by an Ig-like C2-type domain (1 - 2). The cytoplasmic region contains a C-terminal Glu-Thr-Gln-Ile sequence that corresponds to a potential PDZ (postsynaptic density-95/discs large/zona occludens-1) domain-binding motif (1 - 2). Human NGL-1 is 99.7% aa identical to mouse NGL-1. Mouse NGL-1 is highly expressed in the developing cerebral cortex and the striatum at embryonic day 14 (1). Postnatally, NGL-1 is expressed exclusively in the brain, with the highest expression found in the cerebral cortex as a whole, and in individual neocortical areas such as the frontal, parietal and occipital lobes (1). Moderate expression of NGL-1 occurs in the putamen, amygdala, hippocampus and medulla oblongata (1). Weak expression is found in the caudate nucleus and thalamus (1). Functionally, membrane-bound cell-surface NGL-1 binds to netrin-G1 specifically through its LRR region, and in the developing brain, may promote neurite outgrowth of thalamocortical axons (1 - 4). Little is known about NGL-1’s function at later stages.