gap junction channel activity

Definition

Target type: molecularfunction

A wide pore channel activity that enables a direct cytoplasmic connection from one cell to an adjacent cell. The gap junction can pass large solutes as well as electrical signals between cells. Gap junctions consist of two gap junction hemi-channels, or connexons, one contributed by each membrane through which the gap junction passes. [GOC:dgh, GOC:mtg_transport, ISBN:0815340729]

Gap junction channels are specialized intercellular channels that directly connect the cytoplasm of two adjacent cells. They are formed by the alignment of two connexons, which are hemichannels composed of six transmembrane proteins called connexins. Each connexon is embedded in the plasma membrane of one cell, and the two connexons dock together to create a continuous channel.

Gap junctions play a crucial role in cell-to-cell communication by allowing the passage of small molecules, including ions, metabolites, and second messengers, between adjacent cells. This intercellular communication is essential for a wide range of physiological processes, including:

* **Coordination of cellular activity:** Gap junctions enable synchronized activity of cells within tissues, such as the coordinated contraction of cardiac muscle cells or the synchronized firing of neurons.
* **Tissue development and regeneration:** Gap junctions facilitate the exchange of signaling molecules that are involved in cell growth, differentiation, and repair.
* **Metabolic coupling:** Gap junctions allow the transfer of nutrients and metabolites between cells, ensuring that all cells within a tissue have access to essential resources.
* **Electrical coupling:** Gap junctions provide a low-resistance pathway for the flow of electrical currents between cells, enabling rapid propagation of electrical signals.

The molecular function of gap junction channel activity is governed by the properties of connexins and the structure of the gap junction channel itself.

**Connexin Properties:**

* **Connexin diversity:** There are over 20 different connexin genes in mammals, each encoding a unique connexin protein. Different connexins have distinct properties that affect the permeability and regulation of gap junctions.
* **Connexin interactions:** The six connexins within a connexon can interact to form a channel with specific permeability and regulatory properties.
* **Connexin phosphorylation:** Connexins can be phosphorylated by kinases, which can modulate the permeability and gating of gap junction channels.

**Gap Junction Channel Structure:**

* **Channel diameter:** The diameter of the gap junction channel determines the size of molecules that can pass through.
* **Channel selectivity:** The chemical properties of the channel wall can influence the permeability of specific ions and molecules.
* **Channel gating:** Gap junction channels can be opened or closed by a variety of stimuli, including changes in voltage, calcium concentration, or pH.

In summary, the molecular function of gap junction channel activity is a complex process involving the interaction of multiple connexins, their phosphorylation status, and the structural properties of the gap junction channel. These interactions contribute to the diverse roles that gap junctions play in cell-to-cell communication and physiological function.'
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Proteins (2)

Compounds (1)