Sec61 translocon complex binding

Definition

Target type: molecularfunction

Binding to a Sec61 translocon complex. [GOC:pga, PMID:9792704]

The Sec61 translocon complex is a protein channel embedded in the endoplasmic reticulum (ER) membrane, playing a critical role in the translocation of nascent polypeptide chains across the ER membrane. This process is essential for the synthesis and maturation of many proteins destined for secretion, the ER lumen, or other organelles.

The Sec61 complex acts as a "gatekeeper" for protein translocation, ensuring only properly folded and targeted proteins are allowed to enter the ER lumen. It functions through a series of intricate interactions with various components including:

* **Signal Recognition Particle (SRP):** SRP binds to the signal sequence of a nascent polypeptide chain emerging from the ribosome, pausing translation and escorting the ribosome to the ER membrane. The SRP then interacts with the SRP receptor (SR) on the ER membrane, facilitating the handover of the ribosome to the Sec61 complex.
* **Sec62/63 complex:** This complex acts as a chaperone, preventing the newly synthesized polypeptide chain from misfolding or aggregating before entering the ER lumen. It interacts with the Sec61 complex and guides the nascent chain towards the translocon pore.
* **Sec61 complex:** This complex forms the actual protein-conducting channel. It consists of three core components: Sec61α, Sec61β, and Sec61γ. Sec61α is the central component forming the pore, while Sec61β and Sec61γ act as accessory subunits.

The Sec61 translocon complex employs a dynamic mechanism for protein translocation. Initially, the pore is closed, preventing unwanted molecules from entering the ER lumen. When a ribosome carrying a nascent polypeptide chain docks at the Sec61 complex, the pore opens, allowing the polypeptide chain to enter the translocon channel. As the chain moves through the pore, it is guided by the Sec61 complex and the Sec62/63 complex, ensuring its proper folding and translocation.

The Sec61 complex also plays a role in the insertion of transmembrane proteins into the ER membrane. It facilitates the passage of hydrophobic transmembrane domains through the pore while anchoring the protein within the membrane. This involves a complex interplay between the Sec61 complex, the transmembrane domain, and other proteins involved in membrane protein insertion.

In addition to its core function in protein translocation, the Sec61 complex also participates in various cellular processes, including:

* **ER-associated degradation (ERAD):** Defective proteins that fail to fold properly in the ER are recognized and transported back to the cytosol for degradation. The Sec61 complex contributes to this process by facilitating the retrograde translocation of misfolded proteins from the ER lumen.
* **ER stress response:** Under stressful conditions, such as accumulation of misfolded proteins, the Sec61 complex plays a role in triggering the unfolded protein response (UPR), a signaling pathway designed to alleviate stress and restore ER homeostasis.

The Sec61 translocon complex is a highly regulated and dynamic molecular machine crucial for maintaining the integrity and functionality of the ER membrane and its associated cellular processes.'
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Proteins (1)

Compounds (13)