A two-component solution theory is studied which incorporates hydrophobic matching as a major contribution to the lipid-protein interactions in biological membranes. A special geometrical constraint has been discovered which has important implications for the quantitative interpretation of physical effects to lipid-protein interactions. The theory has an advantage over conventional Landau-type phenomenological descriptions in that it accounts for phase separation. A certain class of experimental systems, photosynthetic reaction centre and antenna proteins reconstituted into synthetic lipid membranes of different hydrophobic thicknesses, are considered with a view to determining the parameters of the theory. The theoretical predictions are found to be in good agreement with experimental measurements of shifts in the phase transition temperature.