ARIA can be released from extracellular matrix through cleavage of a heparin-binding domain.
ARIA, or acetylcholine receptor-inducing activity, is a polypeptide that stimulates the synthesis of acetylcholine receptors in skeletal muscle. Here we demonstrate that the ability of ARIA to induce phosphorylation of its receptor in muscle is blocked by highly charged glycosaminoglycans. ARIA constructs lacking the NH2-terminal portion, containing an immunoglobulin-like domain, are fully active and are not inhibited by glycosaminoglycans. Limited proteolysis of ARIA with subtilisin blocks the glycosaminoglycan interaction by degrading this NH2-terminal portion, but preserves the active, EGF-like domain. We also show that ARIA can be released from freshly dissociated cells from embryonic chick spinal cord and cerebellum by either heparin, high salt or limited proteolysis with subtilisin, suggesting that ARIA is bound to the extracellular matrix through charged interactions. We present a model of how ARIA may be stored in extracellular matrix at developing synapses and how its release may be mediated by local proteolysis.
Loeb
J A
JA
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Fischbach
G D
GD
D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins; D002531:Cerebellum / Q000737:chemistry; D002642:Chick Embryo; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D020890:Neuregulin-1; D010766:Phosphorylation; D019000:Phosphotyrosine; D011956:Receptors, Cell Surface / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000378:metabolism*; D011994:Recombinant Proteins; D013116:Spinal Cord / Q000737:chemistry; D013569:Synapses / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D030161:Avian Proteins; C490582:NRG1 protein, Gallus gallus; D009419:Nerve Tissue Proteins; D020890:Neuregulin-1; D011956:Receptors, Cell Surface; D011978:Receptors, Nicotinic; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D006493:Heparin