Hamilton James A
Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA.
Prostaglandins Leukot Essent Fatty Acids. 2007 Nov-Dec;77(5-6):355-61. doi: 10.1016/j.plefa.2007.10.020. Epub 2007 Nov 26.
Recent calculations of the apparent permeability coefficients for long-chain fatty acids (LCFA) in phospholipid bilayers provide a new perspective on their transport in a membrane. LCFA have permeabilities that are many orders of magnitude higher than glucose, amino acids, and ions. Transport of LCFA through membranes must therefore be considered to be much different from these nutrients, and there is no a priori requirement for catalysis by a membrane protein. New evidence indicates that the plasma membrane proteins postulated as catalysts for transporting LCFA into the cell fall into three categories. Some act as enzymes, mainly for the activation of LCFA to the acyl CoA, which is required for subsequent intracellular metabolism of LCFA. Other proteins appear to participate in sequestering and trafficking of LCFA. Finally, some proteins have undefined mechanisms. The established mechanisms are consistent with biophysical properties of LCFA in membranes, including fast free diffusion by "flip-flop" in the phospholipid bilayer.
最近对长链脂肪酸（LCFA）在磷脂双分子层中的表观渗透系数的计算为其在膜中的转运提供了新的视角。LCFA的渗透率比葡萄糖、氨基酸和离子高出许多个数量级。因此，必须认为LCFA通过膜的转运与这些营养物质有很大不同，并且不存在膜蛋白催化的先验要求。新证据表明，被假定为将LCFA转运到细胞中的催化剂的质膜蛋白可分为三类。一些起酶的作用，主要用于将LCFA激活为酰基辅酶A，这是LCFA随后进行细胞内代谢所必需的。其他蛋白质似乎参与了LCFA的隔离和运输。最后，一些蛋白质的机制尚不清楚。已确立的机制与LCFA在膜中的生物物理特性一致，包括通过磷脂双分子层中的“翻转”进行快速自由扩散。
