Argonaute

Argonaute

The Argonaute proteins (Ago proteins) are a family of proteins which are integral to several RNA-silencing processes, including RNA interference (RNAi) and microRNA (miRNA) function. They are named after the Argonauts, a band of heroes in Greek mythology.

Structure

Argonaute proteins are typically around 100 kilodaltons (kDa) in size. They have a characteristic structure that includes two lobes, named the PAZ (Piwi/Argonaute/Zwille) and PIWI (P-element Induced Wimpy testis) lobes. The PAZ lobe is responsible for binding to the 3' end of the guide RNA, while the PIWI lobe contains an RNase H-like domain that can cleave target RNAs.

File:MicroRNAs and Argonaute RNA binding.svg

The structure of an Argonaute protein, showing the PAZ and PIWI lobes.

Function

Argonaute proteins are central to the function of small RNAs in the regulation of gene expression. They bind to small RNAs, such as miRNAs or small interfering RNAs (siRNAs), and guide these RNAs to their target mRNAs. Once bound to the target mRNA, the Argonaute protein can either cleave the mRNA, leading to its degradation, or it can inhibit the translation of the mRNA into protein.

Role in Disease

Alterations in the function of Argonaute proteins have been implicated in several diseases, including cancer. For example, overexpression of Argonaute 2 has been observed in several types of cancer, including breast and colorectal cancer. In addition, mutations in Argonaute proteins have been linked to neurological disorders, such as Amyotrophic lateral sclerosis (ALS) and Frontotemporal dementia (FTD).

See Also

• RNA interference
• microRNA
• small interfering RNA
• Amyotrophic lateral sclerosis
• Frontotemporal dementia