DCL1 (an abbreviation of Dicer-like 1) is a gene in plants that codes for the DCL1 protein, a ribonuclease III enzyme involved in processing double-stranded RNA (dsRNA) and microRNA (miRNA).

[1] Although DCL1, also called Endoribonuclease Dicer homolog 1, is named for its homology with the metazoan protein Dicer, its role in miRNA biogenesis is somewhat different, due to substantial differences in miRNA maturation processes between plants and animals,[2] as well due to additional downstream plant-specific pathways, where DCL1 paralogs like DCL4 participate, such Trans-acting siRNA biogenesis.

In these membraneless organelles, pri-miRNAs are recognized and processes into pre-miRNAs and subsequently into mature miRNA duplexes, by the binding of additional proteins such as Constitutive Alterations in the Small RNAs Pathways9 (CARP9).

[4][5] In animals, the equivalents of these two steps are carried out by different proteins; First, pri-miRNA processing takes place in the nucleus by the ribonuclease Drosha as part of the Microprocessor complex.

[5] Recent single-particle cryo-electron microscopy structures of both complexes of dsRNA structures (pri-RNA and pre-miRNA) as ligand of Arabidopsis DCL1, in cleavage-competent state, suggest that PAZ domain plasticity allow its to get involved in pri-miRNA and pre-miRNA recognition, the possibility of an internal loop binding groove of this protein domain, which serves as an engine that transfers the substrate between two sequential cleavage events.