Recombinant Human Kilon/NEGR1 Protein, CF

Kindred of IgLON (Kilon; also neuronal growth regulator 1 (negr1) and neurotractin) is a 46 kDa member of the IgLON family of molecules. This cell adhesion family includes the proteins LAMP, OBCAM, neurotrimin, CEPU-1, AvGP50, and GP55 (1). Human Kilon is synthesized as a 354 amino acid (aa) precursor that contains a 37 aa signal sequence, a 287 aa mature chain, and a 30 aa propeptide. The mature chain consists of three C2 Ig-like domains, six potential sites for N-linked glycosylation, and a GPI anchor. In addition, there are three sets of cysteines that have the potential to form intradomain disulfide linkages in each of the mature chain's Ig-like domains (1). Human Kilon shares 97% aa sequence identity with mouse and rat Kilon. Expression of Kilon is restricted to the brain, specifically in the cerebrum, brain stem, and hippocampus, with much less expression in the cerebellum (1). In the rat, it was shown that Kilon is already expressed in the E16 stage, and its level gradually increases during development (1). In the cerebral cortex, numerous puncta of Kilon immunoreactivity were visible in all regions, and most were densely distributed in large neurons of layer V (1). These neurons were identified as pyramidal neurons because of their soma location in layer V, large soma size, and extension of their apical dendrite to layer I (1). Kilon may be involved in cell-adhesion and may function as a trans-neural growth-promoting factor in regenerative axon sprouting in the mammalian brain (1 - 2).