Glycosyltransferase proteins

Use of a ligand of a Brainiac protein as a glycosyltransferase inhibitor, wherein said ligand is effective to prevent elongation of a mannose residue linked to a protein via an O-linked glucose residue or via a ceramide in a glycolipid.

Use of a Brainiac protein, or a fragment or functional equivalent of a Brainiac protein, or of a ligand of a Brainiac protein, in the manufacture of a medicament for the treatment of a disease caused by a protein containing one or more EGF-like modules, in which said disease is characterised by a deficiency in glycosylation of mannose residues linked to the protein via an O-linked glucose residue or in glycosylation of mannose residues linked to via a ceramide in a glycolipid.

A method of treating a disease caused by an EGF-like module containing protein, in which there is a deficiency in glycosylation of mannose residues linked to the protein via an O-linked glucose residue or in glycosylation of mannose residues linked to via a ceramide in a glycolipid, said method comprising administering to a patient a Brainiac protein, or a fragment, or functional equivalent of a Brainiac protein, or a ligand of a Brainiac protein.

A Brainiac protein, or a fragment or functional equivalent of a Brainiac protein, for use as a glycosyltransferase, wherein said Brainiac protein, fragment thereof, or functional equivalent thereof acts to elongate a mannose residue linked to a protein via an O-linked glucose residue or via a ceramide in a glycolipid.

A method of transferring a N-acetylglucosamine moiety onto a mannose substrate, whether free or attached to a lipid, carbohydrate or protein, comprising the step of incubating a Brainiac protein, or a fragment, or functional equivalent of a Brainiac protein with said substrate.

A method of screening for a ligand capable of modulating the activity of a Brainiac protein, said method comprising the steps of

• a) contacting a candidate ligand with said Brainiac protein or a fragment thereof;
• and
• b) testing the effect of the ligand on the glycosyltransferase activity of said Brainiac protein, wherein said Brainiac protein or fragment thereof acts to elongate a mannose residue linked to a protein via an O-linked glucose residue or via a ceramide in a glycolipid.

A method of screening for a ligand of a substrate for a Brainiac protein, said method comprising the steps of:

• a) contacting a candidate ligand with said substrate in the presence of a Brainiac protein;
• and
• b) testing the effect of the ligand on the extent of elongation of mannose residues linked to a protein substrate via an O-linked glucose residue or via a ceramide in a glycolipid substrate.