Localization of clathrin light-chain sequences mediating heavy-chain binding and coated vesicle diversity

At least four distinct forms of clathrin light chains are found in mammalian cells1–5. This molecular variability derives from tissue-specific patterns of expression of LCaand LCbgenes6. Sequence analysis shows an overall homology of 60% between LCaand LCband the presence of brain-specific insertion sequences. These findings suggest that the different light chains have both shared and specialized functions6. To address this question we have used a panel of monoclonal antibodies to identify two structurally and functionally distinct regions in the clathrin light-chain sequences. One region (residues 158–208) is exposed in native clathrin structures (triskelions7,8and coated vesicles) and includes the brain-specific insertion sequences. The second region (residues 93–157), which is cryptic in native clathrin structures, is involved in binding the clathrin heavy chain and contains the region of strongest homology with intermediate filament proteins6.