Abstract: The invention provides methods and compositions relating to semaphorin K1 (sema K1) polypeptides which regulate cellular guidance and physiology, and related nucleic acids. The polypeptides may be produced recombinantly from transformed host cells from the disclosed sema K1 encoding nucleic acids or purified from human cells. The invention provides isolated sema K1 hybridization probes and primers capable of specifically hybridizing with the disclosed sema K1 genes, sema K1-specific binding agents such as specific antibodies, and methods of making and using the subject compositions in diagnosis, therapy and in the biopharmaceutical industry.

Abstract: Essentially pure human collapsin and its uses are disclosed. An isolated nucleic acid molecule that comprises a nucleotide sequence that is complementary to a nucleotide sequence that encodes a portion of human collapsin is disclosed. Antibodies that specifically bind to human collapsin and that inhibit its activity are disclosed. Methods of inhibiting the activity of collapsin, methods of inducing neurite outgrowth and methods of treating individuals suffering from nerve damage comprising the step of contacting neuronal cells with nucleic acid molecule that comprises a nucleotide sequence that is complementary to a nucleotide sequence that encodes a portion of human collapsin or comprising the step of contacting a neuronal cell with an antibody that specifically binds to human collapsin are disclosed. Methods of identifying compounds that inhibit the activity of human collapsin comprising the steps of contacting a neuronal cell with human collapsin in the presence of a test compound are disclosed.