Non-specific lipid-mediated interactions between two integral membrane
proteins have been investigated using Monte-Carlo simulations. We hav
e found two different ranges of attraction. A depletion-induced attrac
tion in the range r < sigma(L), where sigma(L), is the diameter of a l
ipid and r is the distance between the surfaces of the two proteins, a
nd a fluctuation-induced attraction in the range 1 < r/sigma(L) < 4 th
at originates from the gradients in the density fluctuations of the li
pids around each protein. (C) 1998 Elsevier Science B.V. All rights re
served.