Studies on glycopeptide released by trypsin from sheep erythrocytes.

Pretreatment of sheep erythrocytes with trypsin abolishes their specific binding and rosette formation with human T lymphocytes. A glycopeptide containing sialic acid is released from the intact sheep erythrocytes by incubation with trypsin and purified. This glycopeptide contains activity that can be bound to T lymphocytes and produces inhibition of rosette formation. This component with a m.w. of about 10,000 contains galactose, acetylglucosamine, acetylgalactosamine, sialic acid, and serine. These results suggest that the glycopeptide released by trypsin treatment may contain the site of the T cell receptor of sheep erythrocytes.