Actin tails are induced by N-WASP (left), which is even more active with extra lysines in its B motif (right).

LIM/ELSEVIER

Alysine-laden sensor makes an actin regulator ultrasensitive to phospholipid levels, according to Venizelos Papayannopoulos, Wendell Lim (University of California, San Francisco, CA), and colleagues.

Phospholipids, particularly PIP2, are activators of N-WASP—an Arp2/3 regulator that turns on actin polymerization. None of the common PIP-binding domains (e.g., Pleckstrin Homology or Phox domains) are found in N-WASP. Instead, a region of 10 basic residues (the B motif) binds to the phospholipids. The new research reveals that this conglomerate of positive charges turns N-WASP into an all-or-nothing switch in response to changing PIP2 density.

At 10% PIP2, N-WASP bound tenfold more strongly to vesicles than it did at 2% PIP2. Even sharper effects from lipid density were seen in actin polymerization...

The Rockefeller University Press
2005
The Rockefeller University Press
2005
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