Final answer:
Recombinant membrane proteins are more mobile in artificial lipid bilayers because these artificial systems lack the complex cytoskeletal attachments, interactions with other proteins, and membrane domains that naturally restrict protein mobility in living cells.
Step-by-step explanation:
Recombinant membrane proteins exhibit increased mobility in artificial lipid bilayers because these systems lack the complex structures and interactions found in natural cell membranes. In a natural cellular environment, membrane proteins are often associated with various elements that restrict their movement. These include interactions with the cytoskeleton, other membrane proteins, and membrane domains such as lipid rafts, which can compartmentalize the cell membrane into distinct regions.
Hence, the natural complexity and cellular structures limit the mobility of membrane proteins in living organisms compared to their mobility in simplified, artificial systems. The fluid mosaic model explains that the plasma membrane is a dynamic and fluid structure with proteins and lipids moving around; however, this is often constrained in natural settings due to the density of interactions and the presence of regulatory mechanisms which are absent in artificial lipid bilayers.