ZC3H3 (zinc finger CCCH-type containing 3) is a nuclear RNA-binding protein that plays critical roles in mRNA export and RNA decay pathways. The protein is required for the export of polyadenylated mRNAs from the nucleus, functioning as a coupling factor between mRNA processing and nuclear export 1. ZC3H3 serves as an essential component of the Poly(A) Tail eXosome Targeting (PAXT) complex, working alongside MTR4, ZFC3H1, RBM26, and RBM27 to facilitate nuclear RNA decay 2. Recent studies reveal ZC3H3's involvement in a sophisticated RNA sorting mechanism where it helps trigger ZFC3H1 conformational changes that activate exosomal degradation of short RNAs with fewer exons, while allowing longer RNAs to proceed to nuclear export 3. Additionally, ZC3H3 functions as an m6A methylation writer, contributing to RNA modification processes 4. The protein demonstrates functional conservation across species, as depletion in both Drosophila and human cells results in mRNA export defects and altered nuclear RNA distribution 1. ZC3H3 has potential clinical significance, with altered expression and methylation patterns observed in various cancers including adrenocortical carcinoma and hepatocellular carcinoma 56.