Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide.
Glycoproteins are important for white blood cell recognition, and play a role in the immune system. A number of hormones including: follicle-stimulating hormone (FSH), luteinizing hormone (LH), Thyroid-stimulating hormone (TSH), human chorionic gonadotropin, alpha-fetoprotein
erythropoietin (EPO), are glycoproteins.