L-histidine import across plasma membrane

Definition

Target type: biologicalprocess

The directed movement of L-histidine from outside of a cell, across the plasma membrane and into the cytosol. [GO_REF:0000075, GOC:TermGenie, PMID:23895341]

The transport of L-histidine across the plasma membrane is a complex process that involves multiple proteins and mechanisms. The primary transporter responsible for L-histidine uptake is the **system L amino acid transporter (LAT)**, a member of the solute carrier family 4 (SLC4). LAT is a heterodimeric protein composed of two subunits: **LAT1 and 4F2hc**. LAT1 is the primary transporter responsible for L-histidine binding and translocation, while 4F2hc is a chaperone protein that aids in the expression and stability of LAT1.

The transport of L-histidine by LAT is **sodium-independent and bidirectional**. This means that L-histidine can move across the plasma membrane in either direction, depending on the concentration gradient. However, under physiological conditions, the concentration of L-histidine is typically higher outside the cell, so LAT primarily functions to transport L-histidine into the cell.

The transport of L-histidine by LAT is also **competitively inhibited by other amino acids**, particularly those with similar structural features to L-histidine. For example, **leucine, isoleucine, and valine** are all known to inhibit L-histidine transport by LAT.

In addition to LAT, other transporters have been shown to contribute to L-histidine uptake. For example, the **system b(0,+)-amino acid transporter (PAT1)**, also known as **SLC6A14**, has been shown to transport L-histidine, although its contribution to overall L-histidine uptake is likely less significant than that of LAT.

The transport of L-histidine across the plasma membrane is tightly regulated, both at the level of transporter expression and activity. This regulation is essential to ensure that cells have access to sufficient L-histidine for protein synthesis and other metabolic processes, while also preventing excessive accumulation of L-histidine, which could be toxic.

**Factors that can influence L-histidine transport include:**

* **The availability of L-histidine in the extracellular fluid.**
* **The activity of the LAT transporter.**
* **The expression levels of LAT and other L-histidine transporters.**
* **The presence of other amino acids that compete for transport by LAT.**

**In summary**, the transport of L-histidine across the plasma membrane is a complex and tightly regulated process that is essential for cellular function. The primary transporter responsible for L-histidine uptake is the LAT transporter, which is a heterodimeric protein composed of LAT1 and 4F2hc. The transport of L-histidine by LAT is sodium-independent, bidirectional, and competitively inhibited by other amino acids. The transport of L-histidine is regulated by a variety of factors, including the availability of L-histidine, the activity of the LAT transporter, the expression levels of LAT and other L-histidine transporters, and the presence of other amino acids that compete for transport by LAT.'
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Proteins (1)

Compounds (1)