Specifically recognizes and binds N6-methyladenosine (m6A)-containing RNAs, and regulates their stability (PubMed:28106072, PubMed:28106076, PubMed:28281539, PubMed:32492408). M6A is a modification present at internal sites of mRNAs and some non-coding RNAs and plays a role in mRNA stability and processing (PubMed:22575960, PubMed:24284625, PubMed:28106072, PubMed:28281539, PubMed:32492408). Acts as a regulator of mRNA stability by promoting degradation of m6A-containing mRNAs via interaction with the CCR4-NOT complex or PAN3 (PubMed:32492408). The YTHDF paralogs (YTHDF1, YTHDF2 and YTHDF3) share m6A-containing mRNAs targets and act redundantly to mediate mRNA degradation and cellular differentiation (PubMed:28106072, PubMed:28106076, PubMed:32492408). Acts as a negative regulator of type I interferon response by down-regulating interferon-stimulated genes (ISGs) expression: acts by binding to FOXO3 mRNAs (By similarity). Binds to FOXO3 mRNAs independently of METTL3-mediated m6A modification (By similarity). Can also act as a regulator of mRNA stability in cooperation with YTHDF2 by binding to m6A-containing mRNA and promoting their degradation (PubMed:28106072). Recognizes and binds m6A-containing circular RNAs (circRNAs); circRNAs are generated through back-splicing of pre-mRNAs, a non-canonical splicing process promoted by dsRNA structures across circularizing exons (PubMed:28281539). Promotes formation of phase-separated membraneless compartments, such as P-bodies or stress granules, by undergoing liquid-liquid phase separation upon binding to mRNAs containing multiple m6A-modified residues: polymethylated mRNAs act as a multivalent scaffold for the binding of YTHDF proteins, juxtaposing their disordered regions and thereby leading to phase separation (PubMed:31388144, PubMed:31292544, PubMed:32451507). The resulting mRNA-YTHDF complexes then partition into different endogenous phase-separated membraneless compartments, such as P-bodies, stress granules or neuronal RNA granules (PubMed:31292544). May also recognize and bind N1-methyladenosine (m1A)-containing mRNAs: inhibits trophoblast invasion by binding to m1A-methylated transcripts of IGF1R, promoting their degradation (PubMed:32194978). Has some antiviral activity against HIV-1 virus: incorporated into HIV-1 particles in a nucleocapsid-dependent manner and reduces viral infectivity in the next cycle of infection (PubMed:32053707). May interfere with this early step of the viral life cycle by binding to N6-methyladenosine (m6A) modified sites on the HIV-1 RNA genome (PubMed:32053707). Interacts with CNOT1; promoting recruitment of the CCR4-NOT complex (PubMed:32492408). Interacts with YTHDF1 (PubMed:28106072). Interacts with YTHDF2 (PubMed:28106072). Interacts with PAN3 (By similarity). Following heat shock stress. The disordered regions have the ability to interact with each other and to 'phase separate' into liquid droplets within the cytosol following binding to mRNAs containing multiple m6A-modified residues (PubMed:31292544). This leads to the partition of m6A-containing mRNAs into membraneless compartments, where mRNAs may be stored, degraded or used to transport mRNAs to dendritic arbors in neurons (PubMed:31292544). (Microbial infection) Proteolytically cleaved by HIV-1 protease when incorporated into HIV-1 particles in a nucleocapsid-dependent-manner. Cleavage by HIV-1 protease probably ensures optimal infectivity of the mature virion. Belongs to the YTHDF family. YTHDF3 subfamily. Was initially reported to act as a regulator of mRNA translation efficiency in cooperation with YTHDF1 by binding to m6A-containing mRNAs and interacting with 40S and 60S ribosome subunits (PubMed:28106072, PubMed:28106076, PubMed:28281539). These studies suggested that the 3 different paralogs (YTHDF1, YTHDF2 and YTHDF3) have unique functions with limited redundancy (PubMed:28106072, PubMed:28106076, PubMed:28281539). However, later studies showed that YTHDF1, YTHDF2 and YTHDF3 paralogs have redundant functions to a profound extent and directly promote degradation of m6A-containing mRNAs (PubMed:32492408). The effect on translation efficiency observed earlier is probably indirect (PubMed:32492408). On the benefits of disorder - Issue 238 of August 2021