THE T-TRANSCRIPTION FACTOR FUNCTIONS AS A DIMER AND EXHIBITS A COMMONHUMAN POLYMORPHISM GLY-177-ASP IN THE CONSERVED DNA-BINDING DOMAIN

T is a transcription factor which activates transcription by binding t o repeated arrangements of the dodecamer 5'-AGGTGTGAAATT3'. Using in v itro synthesised T protein, we have demonstrated that T binds to its t arget DNA as a homodimer and that truncated protein containing only th e N-terminal 233 amino-acid residues, which comprise the DNA-binding d omain, can form a dimer, We also report a common human polymorphism, G ly-177-Asp, within the DNA-binding domain at a position which is a con served glycine residue in T homologues from other vertebrates, The pro position that T forms heterodimers with other members of the T-box tra nscription factor family and the implications for disorders of axial d evelopment are discussed. (C) 1997 Federation of European Biochemical Societies.