Agrin is a 400-600kD heparan sulfate proteoglycan component of the extracellular matrix. The N-terminal half of human Agrin, which mediates ECM interactions, contains a Laminin-binding NtA domain, nine Kazal-type protease inhibitor domains, two Laminin EGF-like domains, and one SEA domain. The C-terminal half contains four EGF-like repeats and three Laminin globular G domains. Rat Agrin lacks the NtA domain, and mouse and chick Agrin include the NtA domain only by the use of an alternate promoter. Additional isoforms are generated by alternate splicing at sites Y and Z in the C-terminal half of rat Agrin (known as A and B, respectively in chick). Agrin isoforms that contain an insert at site Z (Z+ forms) are known as neural Agrin and are selectively produced by motoneurons. Other isoforms are known as muscle Agrin and are additionally expressed in non-neuronal tissues, particularly in basement membranes of the lung and kidney (1-3). This recombinant protein consists of the C-terminal half of human Agrin corresponding to the Z- isoform of rat Agrin. It shares 60-78-80aa sequence identity with comparable regions of chick, mouse, and rat Agrin, respectively. The C-terminal half of Z-and Z+ Agrin binds to a-Dystroglycan and mediates adhesion between motoneurons and myotubes at the neuromuscular junction (NMJ) (4-6). In contrast, only Z+ Agrin is effective at inducing clustering of the postsynaptic Acetylcholine Receptor (AChR) and presynaptic motoneuron differentiation (7, 8). Agrin-induced AChR clustering requires a myotube receptor complex that contains a-Dystroglycan, MuSK, and LRP4 (4, 9-11). Agrin exhibits many functions in addition to NMJ development. It is enriched in senile Alzheimers disease plaques where it binds the AB (1-40) peptide and promotes amyloid fibril formation (12). It regulates neuronal excitability by binding and inhibiting the a3 subunit of the neuronal Na/K ATPase (13). It functions as an epithelial cell attachment receptor for HIV-1 through interactions with the gp41 coat protein (14). During T cell activation, Agrin contributes to formation of the immunological synapse and regulates the threshold of T cell activation (15). Source: Recombinant corresponding to aa1260-2045 of human Agrin, fused with 6-His tag at N-terminal, expressed in CHO cells. Molecular Weight: ~83.5kD Endotoxin Level: 1EU/1ug (LAL) Biological Activity: Measured by the ability of the immobilized protein to support the adhesion of U-87 MG human glioblastoma/astrocytoma cells (ATCC:HTB-14). The typical ED50 for this effect is 0.9-3.6ug/ml after 1h incubation at 37 C. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. Reconstituted product is stable for 6 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
