# IGEM:MIT/2005/TarSummary1

Dimerization seems to be present in the E. Coli chemotaxis pathway. The receptor family that mediates chemotaxis in e. coli has the "same basic topology" as a bunch of eukaryotic TM receptors, consisting of an extrasensory domain connected to a cytoplasmic signalling domain; the connection consists of an ${\displaystyle \alpha }$-helical sequence ${\displaystyle \sim }$20 amino acids long. The aspartate receptor involved in chemotaxis, Tar, is a symmetric homodimer that binds to aspartate, and is of this topology type. Binding of ligand promotes receptor dimerization. In addition to the dimerization that occurs on the extracellular receptor domain, dimerization is necessary to the internal signalling domain.