The present invention provides for a gene, designated as musk, that encodes
a novel tyrosine kinase receptor expressed in high levels in denervated
muscle. The invention also provides for an isolated polypeptide which
activates MuSK receptor. The invention further provides for a polypeptide
which is functionally equivalent to the MuSK activating polypeptide. The
invention also provides assay systems that may be used to detect and/or
measure ligands that bind the musk gene product. The present invention
also provides for diagnostic and therapeutic methods based on molecules
that activate MuSK.
