Isolation and characterization of rat lung Pneumocystis carinii gp120

The principal glycoprotein (gp120) of Pneumocystis carinii obtained from infected rat lung was isolated by differential extraction and size-exclusion chromatography. The purified glycoprotein was cleaved with CNBr to two peptides of approximately 27 and 33 kDa. Amino acid sequences were obtained from both peptides. Proteolytic digestion with V8 protease yielded several peptides and sequences were obtained from peptides of 10 and 19 kDa. The cyanogen bromide cleavage results led to the conclusion that gp120 exists as a homodimer.