Importance of the hexagonal lipid phase in biological membrane organization

Abstract

Domains are present in every natural membrane. They are characterized by a distinctive protein and/or lipid composition. Their size is highly variable from the nano- to the micrometer scale. The domains confer specific properties to the membrane leading to original structure and function. The determinants leading to domain organization are therefore important but remain obscure. This review presents how the ability of lipids to organize into hexagonal II or lamellar phases can promote particular local structures within membranes. Since biological membranes are composed of a mixture of lipids, each with distinctive biophysical properties, lateral and transversal sorting of lipids can promote creation of domains inside the membrane through local modulation of the lipid phase. Lipid biophysical properties have been characterized for long based on in vitro analyses using non-natural lipid molecules; their re-examinations using natural lipids might open interesting perspectives on membrane architecture occurring in vivo in various cellular and physiological contexts.

Features of electron-microscopic visualization of soft phospholipid nanoparicles

“…Thus, EM allows to identify lipid phase state; "traditional" contrasting agents differently identify components in same preparation, suggesting their active interaction with lipid molecules, and indicates necessity of using different contrasting for visualization of lipid nanostructures. Keywords: electron microscopy, negative staining, soft nanoparticles, phospholipids Введение Липиды в водном окружении способны формировать разнообразные наноструктуры: сферические и цилиндрические мицеллы, планарные ламеллярные структуры (бислои) и замкнутые (липосомы), инвертированную гексагональную фазу [1,2]. Это свойство липидов находит широкое применение в биотехнологии и медицине, в частности, наночастицы на ос-нове липидов используют в качестве носителя лекарственных препаратов [3][4][5].…”

Phosphatidic acid and neurotransmission

“…This property of PtdOH is largely ascribed to its well-documented tendency to generate non-bilayer, hexagonal II phase, membrane domains particularly in the presence of calcium ions (Jouhet, 2013). The ability of PtdOH to be fusogenic is in part due to the fact that it is one of the cone-shaped lipids known to promote negative membrane curvature and fusion.…”

Crystallization around solid-like nanosized docks can explain the specificity, diversity, and stability of membrane microdomains

“…To date, however, an increasing amount of evidence supports the existence of such domains in a whole variety of live cells, under physiological conditions, even if they continue to be referred to as exceptional situations (Jouhet, 2013). …”