RISC-loading complex

Definition

Target type: cellularcomponent

A trimeric protein complex required for the formation of a mature RNA-induced silencing complex (RISC). In humans the complex is composed of the endonuclease Dicer (DICER1), TRBP (TARBP2) and the Argonaute protein Ago2 (EIF2C2/AGO2). Within the complex, Dicer and TRBP are required to process precursor miRNAs (pre-miRNAs) to mature miRNAs and then load them onto Ago2. Ago2 bound to the mature miRNA constitutes the minimal RISC and may subsequently dissociate from Dicer and TRBP. This complex has endoribonuclease activity. [GOC:ab, GOC:BHF, GOC:nc, GOC:rph, PMID:18178619, PMID:19820710]

The RISC-loading complex (RLC) is a multi-protein complex involved in the assembly of the 40S ribosomal subunit in eukaryotes. This complex is essential for the efficient and accurate loading of the small ribosomal subunit (40S) with the initiator methionine tRNA (Met-tRNAi). The cellular component of the RLC is mainly localized in the cytoplasm, specifically in the ribosome-free fraction of the cytosol. The complex is composed of several core proteins, including:

**1. Ribosomal proteins (RPs):** These proteins form the structural framework of the ribosome. The specific RPs involved in the RLC vary depending on the organism, but some common members include Rps0, Rps1, Rps2, Rps3a, Rps5, Rps9, Rps14, and Rps19.

**2. Translation initiation factors (eIFs):** These proteins facilitate the initiation of translation. The RLC contains several eIFs, including eIF1, eIF1A, eIF3, eIF5, eIF5B, and eIF6.

**3. Other proteins:** In addition to RPs and eIFs, the RLC also contains a number of other proteins that play important roles in its function. These include:

* **Rcl1:** This protein is essential for the recruitment of the 40S subunit to the RLC and for the efficient loading of Met-tRNAi.
* **Utp1:** This protein is involved in the biogenesis of the 40S subunit and is required for the formation of a stable RLC.
* **Cdc45:** This protein is involved in the regulation of DNA replication and is also required for the stability of the RLC.

The RLC acts as a platform for the assembly of the 40S subunit and the loading of Met-tRNAi. The complex provides a specific environment that allows the 40S subunit to bind to Met-tRNAi and to interact with other translation initiation factors. This process is essential for the efficient initiation of protein synthesis.

The precise molecular mechanisms of RLC function are still under investigation, but it is clear that the complex plays a crucial role in the translation process.'
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Proteins (2)

Compounds (6)