GAG
1. Glycosaminoglycans. Long-branched chains of sugar molecules built from repeating dissacharide subunits containing amino groups. Glycosaminoglycans are present on the surfaces of eukaryotic cells where they are believed to play a role in cell-cell and cell-substate recognition. 2. Group-specifi c antigens. The proteins encoded for by the GAG gene of a retrovirus. The GAG proteins are the components of the virus capsid.