nucleoside import across plasma membrane

Definition

Target type: biologicalprocess

The directed movement of nucleoside from outside of a cell, across the plasma membrane and into the cytosol. [PMID:21998139, PMID:30658162]

Nucleoside import across the plasma membrane is a crucial process for cellular metabolism, enabling cells to acquire essential building blocks for DNA, RNA, and energy production. The process involves a complex interplay of membrane proteins, specific transporter molecules, and concentration gradients. Here's a detailed description:

1. **Membrane Transport Proteins:** The plasma membrane, the outer boundary of a cell, is selectively permeable, meaning it controls the passage of substances in and out. Specific membrane proteins known as nucleoside transporters facilitate the movement of nucleosides across this barrier. These transporters are highly selective, recognizing and binding to particular nucleosides based on their structure and chemical properties.

2. **Types of Transporters:** There are two main classes of nucleoside transporters:
* **Facilitative Transporters:** These transporters move nucleosides down their concentration gradient, from an area of high concentration to an area of low concentration. This movement does not require energy input and is passive. Examples include the equilibrative nucleoside transporter (ENT) family, which includes ENT1 and ENT2.
* **Active Transporters:** These transporters move nucleosides against their concentration gradient, from an area of low concentration to an area of high concentration. This movement requires energy, typically supplied by ATP hydrolysis. Examples include the concentrative nucleoside transporter (CNT) family, which includes CNT1, CNT2, and CNT3.

3. **Transport Mechanism:**
* **Facilitative Transport:** The nucleoside binds to the transporter protein on the outside of the cell. This binding triggers a conformational change in the protein, opening a channel through the membrane. The nucleoside passes through the channel and is released into the cell. The concentration gradient drives the movement of the nucleoside.
* **Active Transport:** The nucleoside binds to the transporter protein on the outside of the cell. This binding is coupled to the hydrolysis of ATP, providing the energy required for movement against the concentration gradient. The nucleoside is then translocated through the membrane and released into the cell.

4. **Regulation:** The activity of nucleoside transporters is regulated by various factors, including:
* **Concentration Gradients:** The concentration of the nucleoside inside and outside the cell influences the direction and rate of transport.
* **pH:** The pH of the cellular environment can affect the activity of some transporters.
* **Cellular Metabolism:** The metabolic needs of the cell can influence the expression and activity of nucleoside transporters.
* **Hormones and Growth Factors:** Certain hormones and growth factors can modulate transporter activity.

5. **Importance:** The import of nucleosides across the plasma membrane is essential for:
* **DNA and RNA Synthesis:** Nucleosides are the building blocks for DNA and RNA, and their availability is crucial for cell growth and replication.
* **Energy Production:** Some nucleosides, like adenosine, are precursors to adenosine triphosphate (ATP), the primary energy currency of the cell.
* **Cell Signaling:** Nucleosides play roles in cell signaling pathways, influencing processes like inflammation, immunity, and neurotransmission.

6. **Disease Relevance:** Dysregulation of nucleoside transport can contribute to various diseases, including:
* **Cancer:** Some cancer cells exhibit increased nucleoside uptake, fueling their rapid growth.
* **Immune Deficiency:** Deficiencies in nucleoside transport can affect immune function, leading to increased susceptibility to infections.
* **Neurological Disorders:** Disruptions in nucleoside transport can affect brain function and contribute to neurological disorders.

In summary, nucleoside import across the plasma membrane is a highly regulated process involving specialized transporter proteins. This process is critical for cellular metabolism, growth, and various physiological functions. Dysregulation of nucleoside transport can have significant consequences for health and disease.'"

Proteins (1)

Compounds (4)