Cell 137, 159–171 (2009)

The connections, or 'synapses', between neurons change in both strength and shape in response to consistent use — a mechanism thought to underpin learning and memory.

Mariko Kato Hayashi of the Massachusetts Institute of Technology in Cambridge and her colleagues now show that the protein Homer forms tetramers — proteins with four subunits — whose multiple facets could help to coordinate signalling and shape changes at excitatory synapses in the central nervous system.

The researchers show that purified Homer filaments self-assemble with globular hubs of the protein Shank to form a mesh-like polymer matrix that can still incorporate other Homer-binding proteins.

A mutant form of Homer disrupted both the tetramer and the Homer–Shank matrix in vitro, and affected synaptic structure and function in cultured neurons and brain slices.