Cryptic I antigen activity and Mycoplasma pneumoniae-receptor activity associated with sialoglycoprotein GP-2 of bovine erythrocyte membranes.

The 250-kDa sialoglycoprotein of bovine erythrocyte membranes, GP-2, has been found to be an exceptionally rich source of branched sialo-oligosaccharides of poly-N-acetyllactosamine (I antigen) type with receptor activity for the human pathogen Mycoplasma pneumoniae. Desialylated GP-2 is the most potent I-active substance thus far tested. Since this glycoprotein is hydrophobic and can be readily re-incorporated into cell membranes, it should be useful in future studies of the mechanism of production of autoantibodies to the I antigen which commonly arise following human infection with M. pneumoniae.