Evidence for a novel cytoplasmic tRNA-protein complex containing the KH-multidomain protein vigilin.

Vigilin, a protein found predominantly in cells and tissues with a high biosynthetic capacity, was isolated in its native form from human HEp-2 cells (A.T.C.C. CCL23) by immunoaffinity chromatography. Vigilin forms part of a novel ribonucleoprotein complex that also contains additional, as yet uncharacterized, proteins. Experimental evidence suggests that the nucleic acids entrapped in this complex are protected from RNase and belong to the tRNA family. Using either a pool of total human RNA or radioactively labelled tRNA (tRNA (Asp**)) in rebinding experiments, we could show that tRNA is selectively recaptured by the RNA-depleted vigilin-containing complex.