GFP-tagged LAT molecules become trapped (blue) at CD2 clusters (light gray).
VALE/ELSEVIER
In active T cells, signal transduction proteins cluster within the plasma membrane, probably to enhance signaling by concentrating the interacting proteins. Popular model mechanisms for clustering involve either lipid rafts or actin. But Douglass and Vale found that the signaling proteins themselves hold clusters together.
In their system, T cell clusters included the LAT adaptor protein, the Lck tyrosine kinase, and the CD2 costimulatory transmembrane protein. LAT and Lck are thought to be raft-localized proteins. But mutation of their raft-localizing regions did not alter LAT or Lck diffusion or clustering. By contrast, mutating LAT residues that are essential for protein–protein interactions prevented LAT clustering....
