RING finger, HC subclass, found in RNA-binding protein MEX3A
MEX3A, also known as RING finger and KH domain-containing protein 4 (RKHD4), is a RNA-binding phosphoprotein that localizes in P-bodies and stress granules, which are two structures involved in the storage and turnover of mRNAs. It has been implicated in the regulation of tumorigenesis. It controls the polarity and stemness of intestinal epithelial cells through the post-transcriptional regulation of the homeobox transcription factor CDX2, which plays a crucial role in intestinal cell fate specification, both during normal development and in tumorigenic processes involving intestinal reprogramming. Moreover, it exhibits a transforming activity when overexpressed in gastric epithelial cells. MEX3A contains two K homology (KH) domains that provide RNA-binding capacity, and a C-terminal C3HC4-type RING-HC finger. Like other MEX-3 family proteins, MEX3A shuttles between the nucleus and the cytoplasm via the CRM1-dependent export pathway.