Immunoelectrophoretic evidence that the human syncytiotrophoblast transferrin receptor is identical to a major plasma membrane antigen present throughout pregnancy.

Crossed immunoelectrophoresis of solubilized syncytiotrophoblast microvillar proteins has been performed through intermediate gels, containing a monospecific antiserum to transferrin, into gels containing an antiserum raised to purified microvilli from term placentae. This technique resolved the microvillar transferrin-receptor complex into its component proteins. Crossed hydrophobic interaction immunoelectrophoresis confirmed that the transferrin receptor is an amphiphilic integral membrane protein. It is also a major antigen of the microvillar membrane and is present throughout pregnancy.