Related Experiment Video

Updated: May 12, 2026

In Vitro Polymerization of F-actin on Early Endosomes
12:15

In Vitro Polymerization of F-actin on Early Endosomes

Published on: August 28, 2017

WHAMM is an Arp2/3 complex activator that binds microtubules and functions in ER to Golgi transport

Kenneth G Campellone1, Neil J Webb, Elizabeth A Znameroski

  • 1Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA. campellone@berkeley.edu

Cell
|July 11, 2008
PubMed

Insights

WHAMM, a novel nucleation-promoting factor, regulates membrane dynamics by linking microtubules and actin polymerization at the Golgi. This protein is crucial for maintaining Golgi structure and anterograde membrane transport.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cytoskeleton Dynamics

Background:

  • The Arp2/3 complex is a key actin nucleator essential for cellular processes.
  • Nucleation-promoting factors (NPFs) regulate Arp2/3 complex activity, particularly in plasma membrane dynamics.

Purpose of the Study:

  • To identify and characterize a novel mammalian nucleation-promoting factor (NPF).
  • To elucidate the role of WHAMM in Golgi structure and membrane transport.

Main Methods:

  • Protein localization studies (cis-Golgi apparatus, membrane transport intermediates).
  • Analysis of WHAMM's modular domains (N-terminal, coiled-coil, WCA segment).
  • Overexpression and depletion studies to assess WHAMM function.

Main Results:

  • WHAMM localizes to the cis-Golgi and tubulo-vesicular transport intermediates.
  • WHAMM contains domains for Golgi membrane association, microtubule binding, and Arp2/3 activation.
  • WHAMM is essential for Golgi structure maintenance and anterograde membrane transport.
  • WHAMM's microtubule interaction facilitates membrane tubulation, while actin assembly promotes tubule elongation.

Conclusions:

  • WHAMM is a novel mammalian NPF regulating membrane dynamics at the Golgi.
  • WHAMM integrates microtubule and actin cytoskeleton functions for membrane transport.
  • WHAMM is critical for Golgi structure and anterograde membrane flow.

More Related Videos

The C. elegans Intestine As a Model for Intercellular Lumen Morphogenesis and In Vivo Polarized Membrane Biogenesis at the Single-cell Level: Labeling by Antibody Staining, RNAi Loss-of-function Analysis and Imaging12:15

The C. elegans Intestine As a Model for Intercellular Lumen Morphogenesis and In Vivo Polarized Membrane Biogenesis at the Single-cell Level: Labeling by Antibody Staining, RNAi Loss-of-function Analysis and Imaging

Published on: October 3, 2017

Micromanipulation Techniques Allowing Analysis of Morphogenetic Dynamics and Turnover of Cytoskeletal Regulators12:52

Micromanipulation Techniques Allowing Analysis of Morphogenetic Dynamics and Turnover of Cytoskeletal Regulators

Published on: May 12, 2018

Related Concept Videos

Generation of Straight or Branched Actin Filaments01:14

Generation of Straight or Branched Actin Filaments

The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Microtubule Associated Proteins (MAPs)01:42

Microtubule Associated Proteins (MAPs)

Microtubule function and architecture are regulated by an array of specialized proteins called microtubule-associated proteins or MAPs. These proteins are widespread across different organisms and have conserved protein motifs, like the multi-TOG domain for tubulin binding found in the CLASP family of MAPs. Some MAPs are lineage-specific based on their conserved domains. Their functions depend upon the cytoskeletal architecture and cell type they are located within. In-plant cells, a specific...
Coat Assembly and GTPases01:33

Coat Assembly and GTPases

Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Rab Proteins01:14

Rab Proteins

Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Mechanism of Lamellipodia Formation01:31

Mechanism of Lamellipodia Formation

Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
Membrane Asymmetry Regulating Transporters01:19

Membrane Asymmetry Regulating Transporters

Enzymes like flippase, floppase, and scramblase transfer phospholipids from one layer to another in the membrane, thereby affecting membrane asymmetry.
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...