Factors that Modulate Membrane Fatty Acid Composition, Structure and Protein Lipid Interactions.

BRENNER R.R.; BERNASCONI A.M.; MONTANARO, M.A.

Mar del Plata, Argentina

Congreso; XLIII Anual Meeting of SAIB (Sociedad Argentina de Bioquimica y Biologia Molecular); 2007

Sociedad Argentina de Investigacion Bioquimica y Biologia Molecular

Dietary component hormones, nuclear receptors like LXR, PPAR, RXR and many exogenous agonists modulate endoplasmic reticulum fatty acid desaturases, that control unsaturated fatty acid biosynthesis and therefore the lipidic composition and packing of membranes and the interaction with proteins. These factors and effects are currently  outlined, measured and discussed. Through the translocon, intrinsic proteins synthesized in the rough endoplasmic reticulum are introduced through hydrophobic interaction with the acyl chains of the phospholipids to the microsomal membrane. Due to the presence of many molecular species of phospholipids in the membranes, with saturated chains bound to sn-1 and unsaturated acids to sn-2 positions preferentially , the existence of different domains is visualized. The domains are of raft-like and non-raft structure. The raft-like domain contain cholesterol and sphingomyelin and cholesterol interaction with saturated acyl chains is a favourable factor whereas unsaturated acids and cholesterol are incompatible. The effect of unsaturated acyl chains in the microsomes, fluidity, and dynamics correlative to alterations of intrinsic enzyme properties is discussed. The case of desaturases and the structure of their four hydrophobic aminoacid chains spanning the ER bilayer is also shown and discussed.