On the variation of the major nuclear envelope (lamina) polypeptides

Three polypeptides which predominate in nuclear envelope and nuclear pore complex-lamina fractions are usually identified by their migration rates in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Unfortunately, their migration relative to proteins frequently used as molecular weight standards can vary significantly under different electrophoresis conditions. However, the three maintain the same order of migration. They have been separated on the basis of both isoelectric point and apparent molecular weight and characterized by their tryptic peptides. Their identity as unique proteins has been established. One appears to be a cleavage product of another while the third has regions of unique sequence. This cleavage model is supported by an in vitro cleavage reaction.