The original fluid mosaic model stated that membrane proteins move freely in the plane of the lipid bilayer via lateral diffusion "like protein icebergs in a sea of lipids." since its initial description in 1927, the fluid mosaic model has been refined. complete the statements that describe some of the refinements of the fluid mosaic model as it relates to protein mobility. within the fluid lipid matrix, may form a locally rigid, non‑lipid matrix. membrane domains that are rich in sphingolipids and cholesterol are called these regions have reduced lipid and protein mobility. reduce protein mobility by attaching to proteins or fencing in proteins.

Membrane domains that are rich in sphingolipids and cholesterol are called specialized lipid domains or lipid rafts

These regions have reduced lipid and protein mobility.  There are different type of regions or domains which could restrict the mobility of lipids and proteins in the membrane so restrictions on the lateral mobility have been linked to binding to extra-cellular matrix, to the formation of specialized membrane nano-domains, such as lipid rafts, specialized lipid submicrodomains around integral membrane proteins and glycoproteins, and to the formation of protein complexes or domains, . Glycoprotein complexes, membrane domains, cytoskeletalinteractions, extracellularmatrix interactions, peripheral membrane protein interactions, lipid–lipid interactions are mechanism through mobility can be restrained.

Reduce protein mobility by attaching to proteins or fencing in proteins. Membrane-associated proteins. These membrane-associated components seems to be involved in stabilizing cell membranes (and thus cells) and immobilizing membrane components outside the cell to the extracellular matrix or across the membrane to cytoskeletal networks inside cells where they can work as parts of adhesion structures or cell motility traction points.