Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Mol Biol Cell. 2012 Jun;23(12):2352-61. doi: 10.1091/mbc.E11-12-1059. Epub 2012 Apr 18.

Multiple repeat elements within the FAM21 tail link the WASH actin regulatory complex to the retromer.

Author information

  • 1Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA.

Abstract

Wiskott-Aldrich syndrome protein (WASPs) control actin dynamics in cellular processes, including cell motility, receptor-mediated endocytosis, bacterial invasion, and vesicular trafficking. We demonstrated that WASH, a recently identified WASP family protein, colocalizes on endosomal subdomains with the cargo-selective complex (CSC) of the retromer, where it regulates retrograde sorting from endosomes in an actin-dependent manner. However, the mechanism of WASH recruitment to these retromer-enriched endosomal subdomains is unclear. Here we show that a component of the WASH regulatory complex (SHRC), FAM21, which contains 21 copies of a novel L-F-[D/E](3-10)-L-F motif, directly interacts with the retromer CSC protein VPS35. Endosomal localization of FAM21 is VPS35 dependent and relies on multivalency of FAM21 repeat elements. Using a combination of pull-down assays and isothermal calorimetry, we demonstrate that individual repeats can bind CSC, and binding affinity varies among different FAM21 repeats. A high-affinity repeat can be converted into a low-affinity one by mutation of a hydrophobic residue within the motif. These in vitro data mirror the localization of FAM21 to retromer-coated vesicles in cells. We propose that multivalency enables FAM21 to sense the density of retromer on membranes, allowing coordination of SHRC recruitment, and consequent actin polymerization, with retromer sorting domain organization/maturation.

PMID:
22513087
[PubMed - indexed for MEDLINE]
PMCID:
PMC3374753
Free PMC Article

Images from this publication.See all images (7)Free text

FIGURE 1:
FIGURE 2:
FIGURE 3;
FIGURE 4:
FIGURE 5:
FIGURE 6:
FIGURE 7:
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk