Determination of the secondary structure and folding topology of an RNA binding domain of mammalian hnRNP A1 protein using three-dimensional heteronuclear magnetic resonance spectroscopy.

The secondary structure and folding topology of the first RNA binding domain of the human hnRNP A1 protein was determined by multidimensional heteronuclear NMR spectroscopy. The 92 amino acid long domain exhibits a beta alpha beta beta alpha beta folding pattern, arranged in a four-stranded antiparallel beta-sheet flanked by two alpha-helices, which is very similar to that found for other members of this family. Regions of marked variation between the structurally characterized RNA binding proteins of this class to date are mainly localized in the loops connecting the secondary structure elements.