et al curr opin struct biol 5 699705 1995 bia is a technology for studying biospecific interactions in real time without labeling any of the interactants e g biacore u2122 changes in the optical phenomenon surface plasmon resonance spr can be used as an indication of real time reactions between biological molecules in yet another aspect of the invention an mttgh polypeptide can be used as a u201c bait protein u201d in a two hybrid assay or three hybrid assay see e g u s pat no 5 283 317 zervos et al cell 72 223232 1993 madura et al j biol chem 268 1204612054 1993 bartel et al biotechniques 14 920924 1993 iwabuchi et al oncogene 8 16931696 1993 and brent wo94 10300 to identify other proteins which bind to or interact with the mttgh polypeptide and modulate its activity in many screening embodiments it may be desirable to immobilize either the mttgh polypeptide or polynucleotide or the test compound to facilitate separation of bound from unbound forms of one or both of the interactants as well as to accommodate automation of the assay thus either the mttgh polypeptide or polynucleotide or the test compound can be bound to a solid support suitable solid supports include but are not limited to glass or plastic slides tissue culture plates microtiter wells tubes silicon chips or.