Defining the repeating elements in the cysteine-rich region (CRR) of the CD18 integrin β2 subunit

Abstract
The cysteine-rich region (CRR) of the integrin β subunits is organised into four repeating elements. By expression of a panel of truncated β2 subunits, and CRR segments fused to the C-terminal end of a CD4 soluble fragment, the segment required for the expression of two monoclonal antibody conformational epitopes was determined. This segment, E482–Q574, contains 16 cysteines representing two repeating units. We have thus defined the CRR unit motif of ‘xC---C---C---CxCxxCxC---Cx’, where ‘x’ represents a single residue, and ‘---’ represents a stretch of four to 14 residues.