fourth type I K homology (KH) RNA-binding domain found in vigilin and similar proteins
Vigilin, also called high density lipoprotein-binding protein, or HDL-binding protein, is a ubiquitous and highly conserved RNA-binding protein that shuttles between nucleus and cytoplasm presumably in contact with RNA molecules. It may be involved in chromosome partitioning at mitosis, facilitating translation and tRNA transport, and control of mRNA metabolism, including estrogen-mediated stabilization of vitellogenin mRNA. Vigilin is up-regulated by cholesterol loading of cells and functions to protect cells from over-accumulation of cholesterol. It may play a role in cell sterol metabolism. Disruption of human vigilin impairs chromosome condensation and segregation. Vigilin has a unique structure of 14-15 consecutively arranged, but non-identical K-homology (KH) domains which apparently mediate RNA-protein binding. The model corresponds to the fourth one.