| WH2 motif | |||||||||
|---|---|---|---|---|---|---|---|---|---|
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| Identifiers | |||||||||
| Symbol | WH2 | ||||||||
| Pfam | PF02205 | ||||||||
| InterPro | IPR003124 | ||||||||
| SMART | WH2 | ||||||||
| SCOPe | 1ej5 / SUPFAM | ||||||||
| |||||||||
| WH2 motif | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| | |||||||||
| Identifiers | |||||||||
| Symbol | WH2 | ||||||||
| Pfam | PF02205 | ||||||||
| InterPro | IPR003124 | ||||||||
| SMART | WH2 | ||||||||
| SCOPe | 1ej5 / SUPFAM | ||||||||
| |||||||||
The WH2 motif or WH2 domain is an evolutionarily conserved sequence motif contained in proteins. [2] It is found in WASP proteins which control actin polymerisation, therefore, WH2 is important in cellular processes such as cell contractility, cell motility, cell trafficking and cell signalling. [3]
The WH2 motif (for Wiskott–Aldrich syndrome homology region 2) has been shown in WAS and Scar1/WASF1 (mammalian homologue) to interact via their WH2 motifs with actin.
The WH2 (WASP-Homology 2, or Wiskott–Aldrich homology 2) domain is an ~18 amino acids actin-binding motif. This domain was first recognized as an essential element for the regulation of the cytoskeleton by the mammalian Wiskott–Aldrich syndrome protein (WASP) family. WH2 proteins occur in eukaryotes from yeast to mammals, in insect viruses, and in some bacteria. The WH2 domain is found as a modular part of larger proteins; it can be associated with the WH1 or EVH1 domain and with the CRIB domain, and the WH2 domain can occur as a tandem repeat. The WH2 domain binds to actin monomers and can facilitate the assembly of actin monomers into actin filaments. [4] [5]
Human genes encoding proteins containing the WH2 motif include:
The Wiskott–Aldrich Syndrome protein (WASp) is a 502-amino acid protein expressed in cells of the hematopoietic system that in humans is encoded by the WAS gene. In the inactive state, WASp exists in an autoinhibited conformation with sequences near its C-terminus binding to a region near its N-terminus. Its activation is dependent upon CDC42 and PIP2 acting to disrupt this interaction, causing the WASp protein to 'open'. This exposes a domain near the WASp C-terminus that binds to and activates the Arp2/3 complex. Activated Arp2/3 nucleates new F-actin.
Wiskott–Aldrich syndrome (WAS) is a rare X-linked recessive disease characterized by eczema, thrombocytopenia, immune deficiency, and bloody diarrhea. It is also sometimes called the eczema-thrombocytopenia-immunodeficiency syndrome in keeping with Aldrich's original description in 1954. The WAS-related disorders of X-linked thrombocytopenia (XLT) and X-linked congenital neutropenia (XLN) may present similar but less severe symptoms and are caused by mutations of the same gene.
Cortactin is a monomeric protein located in the cytoplasm of cells that can be activated by external stimuli to promote polymerization and rearrangement of the actin cytoskeleton, especially the actin cortex around the cellular periphery. It is present in all cell types. When activated, it will recruit Arp2/3 complex proteins to existing actin microfilaments, facilitating and stabilizing nucleation sites for actin branching. Cortactin is important in promoting lamellipodia formation, invadopodia formation, cell migration, and endocytosis.
Actin-related protein 3 is a protein that in humans is encoded by the ACTR3 gene.
Actin-related protein 2 is a protein that in humans is encoded by the ACTR2 gene.
Wiskott-Aldrich syndrome protein family member 2 is a protein that in humans is encoded by the WASF2 gene.
Cytoplasmic protein NCK1 is a protein that in humans is encoded by the NCK1 gene.
Neural Wiskott-Aldrich syndrome protein is a protein that in humans is encoded by the WASL gene.
Wiskott–Aldrich syndrome protein family member 1, also known as WASP-family verprolin homologous protein 1 (WAVE1), is a protein that in humans is encoded by the WASF1 gene.
CD2-associated protein is a protein that in humans is encoded by the CD2AP gene.
WAS/WASL-interacting protein family member 1 (WIP) is a protein that in humans is encoded by the WIPF1 gene.
Ena/VASP-like protein is a member of the Ena/VASP family of proteins that in humans is encoded by the EVL gene.
Wiskott-Aldrich syndrome protein family member 3 is a protein that in humans is encoded by the WASF3 gene.
Protein cordon-bleu is a protein that in humans is encoded by the COBL gene.
The Actin assembly-inducing protein (ActA) is a protein encoded and used by Listeria monocytogenes to propel itself through a mammalian host cell. ActA is a bacterial surface protein comprising a membrane-spanning region. In a mammalian cell the bacterial ActA interacts with the Arp2/3 complex and actin monomers to induce actin polymerization on the bacterial surface generating an actin comet tail. The gene encoding ActA is named actA or prtB.
Beta thymosins are a family of proteins which have in common a sequence of about 40 amino acids similar to the small protein thymosin β4. They are found almost exclusively in multicellular animals. Thymosin β4 was originally obtained from the thymus in company with several other small proteins which although named collectively "thymosins" are now known to be structurally and genetically unrelated and present in many different animal tissues.
Arp2/3 complex is a seven-subunit protein complex that plays a major role in the regulation of the actin cytoskeleton. It is a major component of the actin cytoskeleton and is found in most actin cytoskeleton-containing eukaryotic cells. Two of its subunits, the Actin-Related Proteins ARP2 and ARP3, closely resemble the structure of monomeric actin and serve as nucleation sites for new actin filaments. The complex binds to the sides of existing ("mother") filaments and initiates growth of a new ("daughter") filament at a distinctive 70 degree angle from the mother. Branched actin networks are created as a result of this nucleation of new filaments. The regulation of rearrangements of the actin cytoskeleton is important for processes like cell locomotion, phagocytosis, and intracellular motility of lipid vesicles.
In molecular biology, the IMD domain is a BAR-like domain of approximately 250 amino acids found at the N-terminus in the insulin receptor tyrosine kinase substrate p53 (IRSp53/BAIAP2) and in the evolutionarily related IRSp53/MIM (MTSS1) family. In IRSp53, a ubiquitous regulator of the actin cytoskeleton, the IMD domain acts as conserved F-actin bundling domain involved in filopodium formation. Filopodium-inducing IMD activity is regulated by Cdc42 and Rac1 and is SH3-independent. The IRSp53/MIM family is a novel F-actin bundling protein family that includes invertebrate relatives:
The WAVE regulatory complex (WRC) is a five-subunit protein complex in the Wiskott-Aldrich syndrome protein (WASP) family involved in the formation of the actin cytoskeleton through interaction with the Arp2/3 complex. The holocomplex comprises WAVE1, CYFIP1, ABI2, Nap1 and HSPC300 in its canonical form, or orthologues of these.
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