FLUID MOSAIC MODEL
P.M. may be termed as "protein icebergs in a sea of phospholipids". or Gulab jamun (protiens) in a concentrated solution of sugar (phospholipids).
Two types of proteins are found in P.M.
(i) Integral or intrinsic proteins - Tightly held to phospholipid. These also cover minute pores. These are 70% of the total protein. These proteins may traverse the complete thickness of P.M. Intrinsic protein form channels which provide a rapid passage to water soluble materials across the P.M.
Some intrinsic protein molecules extend through the membrane as single helix on both the sides. These called transmembrane proteins.
(ii) Peripheral or extrinsic proteins - 20-30% of total proteins.