<prompt> On weight basis, the percentage of proteins contain in a cell membrane is:70305080  <response>: Proteins are major constituents of membranes 50 by weight in the plasma membrane. Integral proteins are directly incorporated within the lipid bilayer itself, whereas peripheral proteins exhibit a looser association with one of the two membrane surfaces, paicularly the inner. Ref: 2013. Chapter 2. The Cytoplasm. In Mescher A.L. Eds, Junqueiras Basic Histology: Text Atlas, 13e. 