Hip1R (gold) bridges actin and clathrin.
The protein that forms the link is huntingtin interacting protein 1 related (Hip1R), which was characterized previously as an actin-binding protein that associates with clathrin-coated pits and vesicles. The related protein Hip1 has been implicated in Huntington's disease, where loss of an interaction between normal huntingtin protein and Hip1 may cause problems with membrane– cytoskeletal integrity in the brain.Engqvist-Goldstein et al. now show that Hip1R tightly associates with clathrin during endocytosis and that purified Hip1R both binds to purified clathrin cages and stimulates cage assembly in vitro. They also show that clathrin cages assembled in vitro with Hip1R copellet with F-actin at low speed.
Other workers have induced the formation of clathrin coated pits using only clathrin, two coat proteins, and membranes....
