lamellipodium

Definition

Target type: cellularcomponent

A thin sheetlike process extended by the leading edge of a migrating cell or extending cell process; contains a dense meshwork of actin filaments. [ISBN:0815316194]

Lamellipodia are dynamic, sheet-like protrusions at the leading edge of migrating cells, driven by actin polymerization. They are characterized by a complex and highly organized network of actin filaments, which are arranged in a branched, or dendritic, structure. The lamellipodium contains several distinct sub-structures, each with a unique role in cell migration. These include:
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* **Actin filament network:** This is the core structural element of the lamellipodium. Actin filaments are assembled into a branched network, with barbed ends facing the plasma membrane. This network is highly dynamic, with new filaments constantly being added at the barbed ends and older filaments being disassembled.
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* **Lamellipodium membrane:** The lamellipodium membrane is enriched in various proteins, including adhesion molecules, receptors, and signaling proteins. It is involved in adhesion to the substratum, sensing the environment, and signaling to the cell's interior.
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* **Lamellipodial sheet:** This is the thin, sheet-like structure that extends from the cell body. It is composed of a dense network of actin filaments and associated proteins, which are tightly interconnected.
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* **Lamellipodial filopodia:** These are thin, finger-like projections that extend from the lamellipodium. They are rich in actin filaments and are involved in sensing the environment and guiding cell migration.
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* **Lamellipodial ruffles:** These are transient, wave-like structures that form at the leading edge of the lamellipodium. They are associated with rapid protrusion and are believed to play a role in exploratory behavior.
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* **Lamellipodial Arp2/3 complex:** This protein complex is essential for the formation and maintenance of the branched actin network in the lamellipodium. It nucleates the assembly of new actin filaments and promotes their branching.
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* **Lamellipodial WASP proteins:** These proteins act as activators of the Arp2/3 complex. They bind to the cell membrane and are involved in regulating actin polymerization and lamellipodium protrusion.
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* **Lamellipodial Ena/VASP proteins:** These proteins regulate the organization and dynamics of the actin filaments. They promote the formation of long, unbranched actin filaments and are involved in lamellipodium protrusion.
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* **Lamellipodial cofilin:** This protein promotes actin filament depolymerization, which is important for the turnover of the actin network and for the retraction of the lamellipodium.
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* **Lamellipodial myosin II:** This motor protein is involved in the contraction of the lamellipodium. It generates force to retract the lamellipodium and to move the cell forward.
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* **Lamellipodial signaling molecules:** Various signaling molecules, including Rho GTPases, are localized to the lamellipodium. They regulate the activity of the actin cytoskeleton and other cellular processes involved in cell migration.
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The lamellipodium is a dynamic structure, constantly changing its shape and composition in response to environmental cues. The coordinated activity of these various components allows the lamellipodium to explore the environment, establish adhesion sites, and drive cell migration.'"

Proteins (49)

Compounds (1,274)