Domain mosaic model

Forslind, B. 1994. A domain mosaic model of the skin barrier. Acta Derm Venereol 74 1. 

In 1994 Forslind presented a more structure-function orientated model, the domain mosaic model.38 With the background given previously, the requirements on the stratum corneum barrier can be summarized as follows the barrier should be watertight but still allow a small, controlled amount of water to leak from the system in order to keep the corneocyte keratin hydrated. 

Fenske DB, Thewald JL, Bloom M, Kitson N (1994) Models of stratum corneum intercellular membranes H NMR of macroscopically oriented multilayers. Biophys J 67 1562-1573 Forslind B (1994) A domain mosaic model of the skin barrier. Acta Derm Venereol 74 1-6... 

To describe the behavior of the lipids within the plane of the bilayer, Forsiind [53] has adapted the model originally developed by Singer and Nicholson [54] to describe behavior of lipids and proteins in cellular membranes. Accordingly, the "Domain Mosaic model [53] postulates that the bulk of the stratum comeum lipids segregate into crystalline/ gel domains that are characterized by low permeability. Bordering these domains are highly... 

Perhaps the most important step in the development of our current understanding of biomembranes was the introduction of the fluid mosaic model [28] (Figure 1.4) [40]. This model describes the cell membrane as a fluid two-dimensional lipid bilayer matrix of about 50 A thickness with its associated proteins. It allows for the lateral diffusion of both lipids and proteins in the plane of the membrane [41] but contains little structural detail. This model has been further developed and it has been assumed that the membrane consists of solid domains coexisting with areas of fluid-disordered membrane lipids that may also contain proteins [42]. This concept has... 

The Singer-Nicolson model of the membrane played a very important role in understanding membrane structure and function. However, many properties of biomembranes are not consistent with this model. In recent years, a growing consensus points at more complex membrane structure, which can be characterized as dynamically structured fluid mosaic. Compared with the original fluid mosaic model, the emphasis has shifted from fluidity to mosaicity. Experimental observations have led to the membrane microdomain concept that describes compartmen-talization/organization of membrane components into stable or transient domains. 

To reconcile this apparent contradiction the membrane skeleton fence and anchored transmembrane picket model was proposed (54). According to this model, transmembrane proteins anchored to and lined up along the membrane skeleton (fence) effectively act as a row of posts for the fence against the free diffusion of lipids (Fig. 11). This model is consistent with the observation that the hop rate of transmembrane proteins increases after the partial removal of the cytoplasmic domain of transmembrane proteins, but it is not affected by the removal of the major fraction of the extracellular domains of transmembrane proteins or extracellular matrix. Within the compartment borders, membrane molecules undergo simple Brownian diffusion. In a sense, the Singer-Nicolson model is adequate for dimensions of about 10 x lOnm, the special scale of the original cartoon depicted by the authors in 1972. However, beyond such distances simple extensions of the fluid mosaic model fail and a substantial paradigm shift is required from a two-dimensional continuum fluid to the compartmentalized fluid. 

Figure 3.4 Fluid mosaic model of a biological membrane. This model represents a biological membrane as a sea of lipids with a mosaic of associated proteins either floating on the surface or embedded within a fluid bilayer of lipids. This model is sufficient to describe many phenomena associated with membranes. It has been modified more recently to include the concept of membrane domains constrained over different timescales by interactions among lipids, between lipids and proteins, and between membrane proteins and the cytoskeletal network. (Modified from a public-domain image created by Mariana Ruiz Villarreal.)...

Fatty acids have important roles in membrane structure and there are several ways by which they can potentially influence the functions of membrane proteins (and indeed some intracellular proteins). The fluid mosaic model of membrane structure describes biological membranes as dynamic and responsive structures. It is now also recognized that domains exist in membranes, where lipid-protein and lipid-lipid interactions may be highly... 

Statistical thermodynamic treatments of defect populations have lead to an explanation of existence of grossly nonstoichio-metric crystals in terms of microdomains of ordered structure. The model considers that the nonstoichiometric matrix is made up of a mosaic of small regions of ordered defect-free structures, the microdomains. To account for stoichiometric variation, one can postulate that at least two microdomains with different compositions occur. However, compositional change might simply arise at the surface of the domain. For example, if there are compositionally identical microdomains, one of which is bounded by an anion surface and one by a cation surface, variation in the two populations can give rise to compositional variation. In a strict sense, as each microdomain is ordered, the concept of a defect is redundant, except for... 

Fig. 17 The mosaic-like structure of crystalline micro-aggregate of EP copolymer chains in the pseudo-hexagonal form, where ordered domains of chains locally arranged as in the orthorhombic-, monoclinic- and triclinic-like model structures of Fig. 15, are assembled together. Long-range positional order of chain axes placed at nodes of a pseudo-hexagonal lattice is maintained. Regions enclosed in a different loop delineate domains of chains ordered in the short-range according to the structural models of Fig. 15...

---