Final answer:
The protein within the ECM that has a membrane bilayer-spanning domain is the integral membrane protein. These proteins incorporate into the membrane via their hydrophobic regions and can extend through the entire membrane.
Step-by-step explanation:
The protein of the extracellular matrix (ECM) that has a membrane bilayer-spanning domain is an integral membrane protein. These proteins are characterized by regions that are hydrophobic and which interact with the hydrophobic interior of the membrane, thereby spanning the entire membrane. They are different from fibrillar collagens, which form a structural network but do not span the membrane, and heparan sulfate proteoglycans, which are attached to the exterior of cells. Integral membrane proteins can have hydrophilic regions facing the cytosol or cell exterior while being anchored within the membrane through their hydrophobic regions.