What type of glycoprotein consists of a core protein with many carbohydrate chains attached?

The type of glycoprotein that consists of a core protein with many carbohydrate chains attached is proteoglycans. These molecules play essential roles in the extracellular matrix and cellular signaling. The core protein serves as a backbone to which numerous glycosaminoglycan (GAG) chains are covalently linked. This unique structure allows proteoglycans to retain water and contribute to the hydration and resilience of tissues, particularly in cartilage. The large, negatively charged carbohydrate chains attract water and facilitate nutrient diffusion, as well as providing lubrication.

In contrast, fibronectin, collagen, and integrins are also important components of the extracellular matrix but do not primarily fit the definition of a glycoprotein with extensive carbohydrate attachment like proteoglycans. Fibronectin is involved in cell adhesion and has fewer carbohydrate attachments compared to proteoglycans. Collagen provides structural integrity to connective tissues and is primarily composed of protein without the extensive carbohydrate components characteristic of proteoglycans. Integrins are transmembrane proteins that facilitate cell adhesion and communication but are not classified as glycoproteins with a core protein structure supported by multiple carbohydrate chains.