The pathogenesis of Heymann nephritis, a rat model of human membranous glomerulonephritis, depends on the interaction of autoantibodies with a renal glycoprotein (GP330) on glomerular podocytes. Partial complementary DNAs coding for GP330 were isolated and sequenced. The deduced amino acid sequence from 4.3 kilobases of complementary DNA contains the sequences identical to two peptides derived from the isolated glycoprotein. The deduced amino acid sequence of this protein contains regions with homology to the human low density lipoprotein (LDL) receptor, an indication that GP330 and the LDL receptor may be members ofthe same gene family. Autoantibodies from the kidneys of rats with Heymann nephritis reacted with a nonglycosylated segment of GP330 that contains cysteine-rich 40-amino acid repeats, which are also features of the LDL receptor. GP330 is also similiar in some regions to the mouse epidermal growth factor precursor.