MicroRNA terms

A collection of key terms and definitions regarding microRNA and its biogenesis processes to aid in exam preparation.

microRNA (miRNA)

Small (~22 nt), non-coding RNA that regulates gene expression post-transcriptionally by suppressing target mRNAs, usually via the 3′ UTR.

Pri-miRNA (primary miRNA)

Initial long RNA transcript produced by RNA polymerase II that contains one or more miRNA hairpins.

Pre-miRNA (precursor miRNA)

~70-nt hairpin RNA generated from pri-miRNA after nuclear processing.

Drosha

Nuclear RNase III enzyme that cleaves pri-miRNA into pre-miRNA.

DGCR8

RNA-binding protein that partners with Drosha to recognize and process pri-miRNA.

Exportin-5

Nuclear export receptor that transports pre-miRNA from nucleus to cytoplasm in a Ran-GTP–dependent manner.

Ran-GTPase

Small GTPase that regulates nuclear transport by cycling between GTP- and GDP-bound states.

Ran-GEF

Guanine nucleotide exchange factor that converts Ran-GDP to Ran-GTP (active form) in the nucleus.

Ran-GAP

GTPase-activating protein that stimulates GTP hydrolysis, converting Ran-GTP to Ran-GDP in the cytoplasm.

Small GTPase

Molecular switch that alternates between inactive GDP-bound and active GTP-bound states.

Effector

Downstream protein that binds a small GTPase only in its active (GTP-bound) form to carry out a function.

Nuclear Pore Complex (NPC)

Large protein complex that forms channels in the nuclear envelope and regulates transport between nucleus and cytoplasm.

Dicer

Cytoplasmic RNase III enzyme that processes pre-miRNA into a ~22-nt miRNA duplex.

PACT

Dicer-associated protein that helps regulate miRNA processing and RISC assembly.

TRBP

Dicer-binding protein that stabilizes miRNA processing and assists RISC loading.

AGO (Argonaute)

Core protein of RISC that binds miRNA and mediates gene silencing.

RISC-complex (RNA-induced silencing complex)

Protein–RNA complex containing miRNA and AGO that targets mRNAs for repression or degradation.

Translational repression

Reduction of protein synthesis from an mRNA without necessarily degrading the mRNA.

GTP hydrolysis

Conversion of GTP to GDP that inactivates GTPases and triggers cargo release during nuclear export.