What may a glycoprotein that extends from the surface of a cell do?

A glycoprotein that extends from the surface of a cell primarily functions in cell recognition and communication. It can serve as a receptor for signaling molecules, facilitating interactions with other cells or extracellular matrix components. Additionally, glycoproteins play a crucial role in immune response, allowing the immune system to identify foreign cells or pathogens. Their carbohydrate chains also contribute to cell adhesion and stability in tissues.