fourth type I K homology (KH) RNA-binding domain found in far upstream element-binding protein 3 (FUBP3) and similar proteins
FUBP3, also called FUSE-binding protein 3, or MARTA2, was previously shown to mediate dendritic targeting of MAP2 mRNA in neurons. It may interact with single-stranded DNA from the far-upstream element (FUSE) and activate gene expression. It is required for beta-actin mRNA localization. It also interacts with fibroblast growth factor 9 (FGF9) 3'-UTR UG repeats and positively controls FGF9 expression through increasing translation of FGF9 mRNA. FUBP3 contains four K-homology (KH) RNA-binding domains. The model corresponds to the fourth one.
Comment:Essential to the KH domain, the RNA-binding platform is a strictly conserved GXXG motif, located within a flexible loop between alpha1 and alpha2. This GXXG motif, in concert with a variable loop located between beta2 and beta', functions to clamp an RNA substrate in place upon binding.
Jiyao W et al.(2023). "The conserved domain database in 2023.",