Serrate fragments and derivatives

A substantially purified fragment of a Serrate protein which is the portion of the Serrate protein with the greatest homology over a sequence of 199 amino acids to the amino acid sequence as depicted in FIGS. 15A-15B (SEQ ID NO:9) from about amino acid numbers 85-283, which fragment lacks one or more amino acids of the extracellular domain of the Serrate protein.

A substantially purified fragment of a Serrate protein which is the portion of the Serrate protein with the greatest homology over a sequence of 204 amino acids, to the amino acid sequence as depicted in FIGS. 15A-15B (SEQ ID NO:9) from about amino acid numbers 79-282, which fragment lacks one or more amino acids of the extracellular domain of the Serrate protein.

A substantially pure derivative of a Serrate protein, which derivative is characterized by the ability in vitro, when expressed on the surface of a first cell, to bind to a Notch protein expressed on the surface of a second cell, the derivative having an insertion, substitution, or deletion of one or more amino acids in at least the extracellular domain of the Serrate protein.

A substantially purified fragment of a Serrate protein consisting essentially of amino acid numbers 79-282 of the amino acid sequence as depicted in FIGS. 15A-15B (SEQ ID NO:9), which fragment is characterized by the ability in vitro, when expressed on the surface of a first cell, to bind to a Notch protein expressed on the surface of a second cell.

A substantially purified fragment of a Serrate protein consisting essentially of amino acid numbers 85-283 of the amino acid sequence as depicted in FIGS. 15A-15B (SEQ ID NO:9), which fragment is characterized by the ability in vitro, when expressed on the surface of a first cell, to bind to a Notch protein expressed on the surface of a second cell.