STRUCTURAL DIVERSITY OF LEUCINE-RICH REPEAT PROTEINS

The superfamily of leucine-rich repeat proteins can be subdivided into at least six subfamilies, characterised by different lengths and cons ensus sequences of the repeats. It was proposed that the repeats from different subfamilies retain a similar superhelical fold, but differ i n the three-dimensional structures of individual repeats. The sequence -structure relationship of three new subfamilies was examined by molec ular modelling; I provide structural models for the repeats of all sub families. The models enable me to explain residue conservations within each subfamily. Furthermore, the difference in the packing explains w hy the repeats from different subfamilies never occur simultaneously i n the same protein. Finally, these studies suggest different evolution ary origins for the different subfamilies. The approach used for the p rediction of the leucine-rich repeat protein structures can be applied to other proteins containing internal repeats of about 20 to SO resid ue in length. (C) 1998 Academic Press Limited.