Identification of group specific component/vitamin D-binding protein (GC/DBP) mutants by isoelectric focusing in immobilized pH gradients.

The six common genetic types of the group specific component/vitamin D-binding protein (GC/DBP) system are usually classified by isoelectric focusing in carrier ampholytes, followed by visualization of the GC proteins by immunoprinting with monospecific antiserum. In addition, more than 120 mutant GC types have been discovered. For their identification additional methods were necessary, including polyacrylamide gel electrophoresis, isoelectric focusing in the presence of 3 M urea as well as isoelectric focusing in immobilized pH gradients. The application of the last method is described in detail and several examples of GC/DBP mutants identified thereby are presented.