Molecular Biology and Evolution 19:959-963 (2002)
© 2002 Society for Molecular Biology and Evolution
Evolution of Ribonuclease Inhibitor by Exon Duplication
*Department of Biochemistry
Department of Chemistry, University of Wisconsin–Madison
The leucine-rich repeat (LRR) is a prevalent structural motif that mediates specific protein-protein interactions (Kobe and Deisenhofer 1995b
). The LRR is defined by a region of 20–29 residues that contains the consensus sequence: XLXXLXLXXN, where L, N, and X are leucine, asparagine, and any residue, respectively. Typically, LRRs are displayed in 1–30 tandem copies within a protein.
The first crystalline structure of an LRR-containing protein revealed a new protein fold (Kobe and Deisenhofer 1993
) (fig. 1A and B
). In porcine ribonuclease inhibitor (RI [Hofsteenge 1997
]), the LRRs are arranged tandemly in a horseshoe shape with 16 
-helices encasing a parallel ß-sheet of 17 strands. Hydrophobic forces between the consensus leucine residues appear to stabilize the ß-sheet. RI is able to bind tightly to members of the ribonuclease (RNase) A superfamily, which not only catalyze RNA degradation but also mediate angiogenesis, cytotoxicity, and the
Acknowledgements
Footnotes
References