RING finger, HC subclass, found in RNA-binding protein MEX3C
MEX3C, also known as RING finger and KH domain-containing protein 2 (RKHD2), or RING finger protein 194 (RNF194), is a RNA-binding phosphoprotein that acts as a suppressor of chromosomal instability. It functions as a RNA-binding ubiquitin E3 ligase responsible for the post-transcriptional, HLA-A allotype-specific regulation of MHC class I molecules (MHC-I). It also modifies retinoic acid inducible gene-1 (RIG-I) in stress granules and plays a critical role in eliciting antiviral immune responses. Moreover, MEX3C plays an essential role in normal postnatal growth via enhancing the local expression of insulin-like growth factor 1 (IGF1) in bone. It may also be involved in metabolic regulation of energy balance. MEX3C 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, MEX3C shuttles between the nucleus and the cytoplasm via the CRM1-dependent export pathway.