The present invention provides a novel family of polypeptides which are ligand-gated channel receptor accessory molecules or ligands, denoted Lynx. This invention provides an isolated polypeptide comprising an amino acid sequence of a Lynx polypeptide in which the amino acid sequence is set forth in SEQ ID NO:2, SEQ ID NO:4, or SEQ ID NO:15, including fragments, mutants, variants, analogs, homologs, or derivatives of the amino acid sequences set forth in SEQ ID NO:2, SEQ ID NO:4, or SEQ ID NO:15. This invention further provides an isolated immunogenic polypeptide; an isolated nucleic acid; pharmaceutical compositions and diagnostic and therapeutic methods of use of the isolated polypeptides and nucleic acids of the present invention; assays for compounds which mimic, alter or inactivate the polypeptides of the present invention for use in therapy; and methods of isolating Lynx polypeptides and the nucleic acids encoding such polypeptides.