Lens lipids

Energetics and kinetics of membrane permeation of photoresists for bioprinting

“…Furthermore, we investigated the influence of introducing cholesterol into a 16:0 PC 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DOPC) GUV (i.e ∼ 40:60 DOPC:Cholesterol mol ratio). Note that this corresponds to a high concentration compared to what is typically found in plasma membranes [44], although still manifested in some instances, such as the eye lens [45,46,47]. Despite the high cholesterol content, we observed only a slight decrease in permeation kinetics (Figure 5B).…”

Energetics and kinetics of membrane permeation of photoresists for bioprinting

“…Furthermore, we investigated the influence of introducing cholesterol into a 16:0 PC 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DOPC) GUV (i.e ∼ 40:60 DOPC:Cholesterol mol ratio). Note that this corresponds to a high concentration compared to what is typically found in plasma membranes [44], although still manifested in some instances, such as the eye lens [45,46,47]. Despite the high cholesterol content, we observed only a slight decrease in permeation kinetics (Figure 5B).…”

Structure and dynamics of cholesterol-mediated aquaporin-0 arrays and implications for lipid rafts

“…Lens membranes contain more cholesterol than is represented by the AQP0 2SM:1Chol structure. Therefore, we determined the structure of AQP0 2D crystals that were grown at a molar sphingomyelin:cholesterol ratio of 1:2, which is close to the lipid composition of human lens core membranes ( Fleschner and Cenedella, 1991 ; Zelenka, 1984 ). These crystals were even better ordered, and electron diffraction patterns of untilted specimens showed reflections to a resolution better than 1.6 Å ( Figure 2C ).…”

“…This model is specific for the formation of AQP0 arrays in lens membranes, but we speculate that similar principles may underlie the organization of lipid rafts. AQP0 may be special in that it forms tetramers and thus has four deep cholesterol-binding sites, so that the avidity effect allows it to form much larger domains than seen for typical lipid rafts ( Simons and Ikonen, 1997 ; Zelenka, 1984 ). In addition, it is presumably not common that the same protein has surfaces that can interact with both the smooth α and the rough β face of cholesterol.…”

Effect of Lipid Head Groups on Double-Layered Two-Dimensional Crystals Formed by Aquaporin-0

“…These crystals demonstrate that lipid head groups can influence the interactions between membrane proteins, but it is unlikely that they affect the physiological interactions that occur between AQP0 arrays in adjacent lens fiber cells. Lens fiber cell membranes contain high concentrations of sphingolipids and cholesterol, two neutral lipid species, no detectable levels of PG, and very small quantities of PS and PA [ 23 ]. In membranes formed from zwitterionic lipids, AQP0 always adopts the p 422 crystal form, in which the junctional interactions are mediated by exposed proline residues on the extracellular loops.…”

Energetics and kinetics of membrane permeation of photoresists for bioprinting

“…Furthermore, we investigated the influence of introducing cholesterol into a 16:0 PC 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DOPC) GUV (i.e ∼ 40:60 DOPC:Cholesterol mol ratio). Note that this corresponds to a high concentration compared to what is typically found in plasma membranes [44], although still manifested in some instances, such as the eye lens [45,46,47]. Despite the high cholesterol content, we observed only a slight decrease in permeation kinetics (Figure 5B).…”

Structure and dynamics of cholesterol-mediated aquaporin-0 arrays and implications for lipid rafts

“…Lens membranes contain more cholesterol than is represented by the AQP0 2SM:1Chol structure. Therefore, we determined the structure of AQP0 2D crystals that were grown at a molar sphingomyelin:cholesterol ratio of 1:2, which is close to the lipid composition of human lens core membranes ( Fleschner and Cenedella, 1991 ; Zelenka, 1984 ). These crystals were even better ordered, and electron diffraction patterns of untilted specimens showed reflections to a resolution better than 1.6 Å ( Figure 2C ).…”

“…This model is specific for the formation of AQP0 arrays in lens membranes, but we speculate that similar principles may underlie the organization of lipid rafts. AQP0 may be special in that it forms tetramers and thus has four deep cholesterol-binding sites, so that the avidity effect allows it to form much larger domains than seen for typical lipid rafts ( Simons and Ikonen, 1997 ; Zelenka, 1984 ). In addition, it is presumably not common that the same protein has surfaces that can interact with both the smooth α and the rough β face of cholesterol.…”

Effect of Lipid Head Groups on Double-Layered Two-Dimensional Crystals Formed by Aquaporin-0

“…These crystals demonstrate that lipid head groups can influence the interactions between membrane proteins, but it is unlikely that they affect the physiological interactions that occur between AQP0 arrays in adjacent lens fiber cells. Lens fiber cell membranes contain high concentrations of sphingolipids and cholesterol, two neutral lipid species, no detectable levels of PG, and very small quantities of PS and PA [ 23 ]. In membranes formed from zwitterionic lipids, AQP0 always adopts the p 422 crystal form, in which the junctional interactions are mediated by exposed proline residues on the extracellular loops.…”

Energetics and kinetics of membrane permeation of photoresists for bioprinting

“…Furthermore, we investigated the influence of introducing cholesterol into a 16:0 PC 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DOPC) GUV (i.e ∼ 40:60 DOPC:Cholesterol mol ratio). Note that this corresponds to a high concentration compared to what is typically found in plasma membranes [44], although still manifested in some instances, such as the eye lens [45,46,47]. Despite the high cholesterol content, we observed only a slight decrease in permeation kinetics (Figure 5B).…”

Structure and dynamics of cholesterol-mediated aquaporin-0 arrays and implications for lipid rafts

“…Lens membranes contain more cholesterol than is represented by the AQP0 2SM:1Chol structure. Therefore, we determined the structure of AQP0 2D crystals that were grown at a molar sphingomyelin:cholesterol ratio of 1:2, which is close to the lipid composition of human lens core membranes ( Fleschner and Cenedella, 1991 ; Zelenka, 1984 ). These crystals were even better ordered, and electron diffraction patterns of untilted specimens showed reflections to a resolution better than 1.6 Å ( Figure 2C ).…”

“…This model is specific for the formation of AQP0 arrays in lens membranes, but we speculate that similar principles may underlie the organization of lipid rafts. AQP0 may be special in that it forms tetramers and thus has four deep cholesterol-binding sites, so that the avidity effect allows it to form much larger domains than seen for typical lipid rafts ( Simons and Ikonen, 1997 ; Zelenka, 1984 ). In addition, it is presumably not common that the same protein has surfaces that can interact with both the smooth α and the rough β face of cholesterol.…”

Effect of Lipid Head Groups on Double-Layered Two-Dimensional Crystals Formed by Aquaporin-0

“…These crystals demonstrate that lipid head groups can influence the interactions between membrane proteins, but it is unlikely that they affect the physiological interactions that occur between AQP0 arrays in adjacent lens fiber cells. Lens fiber cell membranes contain high concentrations of sphingolipids and cholesterol, two neutral lipid species, no detectable levels of PG, and very small quantities of PS and PA [ 23 ]. In membranes formed from zwitterionic lipids, AQP0 always adopts the p 422 crystal form, in which the junctional interactions are mediated by exposed proline residues on the extracellular loops.…”