No need for a new membrane model.

Schindler et al. recently reported lateral diffusion measurements in reconstituted membranes of phospholipid (PL), lipoplysaccharide (LPS) and Escherichia coli matrix protein (P), using the technique of fluorescence recovery after photobleaching (FRAP). Evaluation of their data led Schindler et al. to conclude that the fluid mosaic model is an inadequate description of the membrane and to propose a new membrane model. Their conclusion was based on identifying the fluid mosaic model with a particular binding behaviour of LPS to matrix protein. I present here a more general model for the association of membrane components, and demonstrate the use of lateral diffusion data in elucidating membrane structure. The data of Schindler et al. are shown to be reasonably interpretable on the basis of an association of LPS and matrix protein, which obviates the necessity for postulating a new membrane model.