RESUMO
ARGONAUTE (AGO) proteins are integral parts of regulatory pathways under the control of small RNA (sRNA) that are fundamental for the proper functioning of eukaryotic cells. AGOs, as highly specialized platforms binding specific sRNA, coordinate gene silencing through interaction with other protein factors (forming the RNA-induced silencing complex, RISC), contributing to endonucleolytic cleavage of the target mRNA and/or influencing the translation process. The increasing number of evidence confirms the participation of AGO proteins in several other cellular processes, such as i.e.: transcription regulation, sequestration, RNA-dependent methylation of DNA, repair of DNA damages, synthesis of siRNA independent of DCL (DICER-like) proteins, or co-transcriptional regulation of MIRNA genes expression and intron splicing. Particular plant species are characterized by the presence of a different number of AGO proteins, in many cases of yet unknown regulatory and/or biological function. This review article covers the current knowledge about the functions of AGOs in cell biology and plant development.