Cholesterol Dependent Recruitment of di22:6-PC by a G Protein-Coupled Receptor into Lateral Domains

Polozova, Alla; Litman, Burton J.

doi:10.1016/s0006-3495(00)76502-7

Cited by 116 publications

(91 citation statements)

References 51 publications

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“…A correlation between lipid organization in the context of a membrane raft, phototransduction, and lipid and protein sorting is in the early stages of characterization. Recent model membrane studies suggest that cholesterol is necessary for the recruitment of polyunsaturated fatty acids by rhodopsin into membrane microdomains (25). Similar studies also demonstrated the requirement for specific lipids in the activation process of rhodopsin (26 -28), in transducin binding (29), and in phosphodiesterase activation (30).…”

mentioning

confidence: 85%

Association of a Photoreceptor-specific Tetraspanin Protein, ROM-1, with Triton X-100-resistant Membrane Rafts from Rod Outer Segment Disk Membranes

Boesze‐Battaglia¹,

Dispoto²,

Kahoe³

2002

Journal of Biological Chemistry

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This study reports the isolation and characterization of a Triton X-100-resistant membrane fraction from homogenates of rod outer segment (ROS) disk membranes purified free of the surrounding plasma membrane. A portion of the ROS disk membrane was found to be resistant to Triton X-100 extraction at 4°C. This detergent-resistant fraction was isolated as a low buoyant density band on sucrose density gradients and exhibited an increase in light scattering detected at 600 nm. Biochemical analysis of the Triton X-100-resistant fraction showed it to be enriched in cholesterol and sphingomyelin relative to phospholipid and in phospholipid relative to protein compared with the soluble fraction. The Triton X-100-resistant membranes described herein did not arise simply from partial solubilization of the ROS disk membranes because detergent-treated low buoyant density fractions isolated from homogenates with octyl glucopyranoside had cholesterol and sphingomyelin content indistinguishable from that of solubilized ROS disk homogenates. Analysis of proteins associated with the Triton X-100-resistant fraction showed it to be enriched in the rim-specific protein ROM-1 and caveolin; surprisingly, the fusion protein peripherin/rds (where rds is retinal degeneration slow), also localized to the disk rim, was entirely absent from the membrane raft domain. The lipid profiles of the Triton X-100-resistant membranes were virtually identical in preparations homogenized in either the light or dark. Slightly more ROM-1 was recovered from samples prepared in the light (23%) than from samples prepared in the dark (13%), but peripherin/rds could not be detected in either preparation. When the Triton X-100-resistant membranes were treated with methyl-␤-cyclodextran to deplete membrane cholesterol, the resultant membranes contained slightly lower levels of ROM-1, specifically in the dimeric form. Cholesterol depletion also resulted in the collapse of the large caveolin complex to monomeric caveolae. The results presented herein characterize a pool of ROM-1, a photoreceptor tetraspanin protein, that may play a regulatory role in peripherin/rds-dependent fusion.Photoreceptor rod cells are responsible for vision under dim light. These unique post-mitotic cells are made up of a rod inner segment and a rod outer segment (ROS) 1 region. The ROS contains a stack of closed membranous sacs, referred to as disks, that contain the photoreceptor rhodopsin and that provide the requisite lipid environment for the initial events of phototransduction. There is a continual turnover of disk membranes and the proteins contained therein. Through coordinated processes of disk renewal at the base of the outer segment and disk shedding at the apical tip, the outer segment region is maintained at a constant length, and the physiologic function of light transduction is maintained (1). Interestingly, although the distribution of the major proteins within disks remains constant during the basal-to-apical transit of disks, a process that requires 10 days in the verteb...

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mentioning

confidence: 85%

Association of a Photoreceptor-specific Tetraspanin Protein, ROM-1, with Triton X-100-resistant Membrane Rafts from Rod Outer Segment Disk Membranes

Boesze‐Battaglia¹,

Dispoto²,

Kahoe³

2002

Journal of Biological Chemistry

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“…The ability of the lipids and rhodopsin to organize into complex lateral domains has also been investigated by Litman and colleagues. Their studies showed that there is a cholesterol-dependent recruitment of di22:6-PC by rhodopsin into lateral domains of the disk bilayer [106]. The cluster of rhodopsin and the lipids that formed this domain exceeded two adjacent lipid layers.…”

Section: Organization Of Cholesterol In Disk Membranesmentioning

confidence: 99%

The role of cholesterol in rod outer segment membranes

Albert

Boesze‐Battaglia

2005

Progress in Lipid Research

111

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The photoreceptor rod outer segment (ROS) provides a unique system in which to investigate the role of cholesterol, an essential membrane constituent of most animal cells. The ROS is responsible for the initial events of vision at low light levels. It consists of a stack of disk membranes surrounded by the plasma membrane. Light capture occurs in the outer segment disk membranes that contain the photopigment, rhodopsin. These membranes originate from evaginations of the plasma membrane at the base of the outer segment. The new disks separate from the plasma membrane and progressively move up the length of the ROS over the course of several days. Thus the role of cholesterol can be evlauated in two distinct membranes. Furthermore, because the disk membranes vary in age it can also be investigated in a membrane as a function of the membrane age. The plasma membrane is enriched in cholesterol and in saturated fatty acids species relative to the disk membrane. The newly formed disk membranes have 6-fold more cholesterol than disks at the apical tip of the ROS. The partitioning of cholesterol out of disk membranes as they age and are apically displaced is consistent with the high PE content of disk membranes relative to the plasma membrane. The cholesterol composition of membranes has profound consequences on the major protein, rhodopsin. Biophysical studies in both model membranes and in native membranes have demonstrated that cholesterol can modulate the activity of rhodopsin by altering the membrane hydrocarbon environment. These studies suggest that mature disk membranes initiate the visual signal cascade more effectively than the newly synthesized, high cholesterol basal disks. Although rhodopsin is also the major protein of the plasma membrane, the high membrane cholesterol content inhibits rhodopsin participation in the visual transduction cascade. In addition to its effect on the hydrocarbon region, cholesterol may interact directly with rhodopsin. While high cholesterol inhibits rhodopsin activation, it also stabilizes the protein to denaturation. Therefore the disk membrane must perform a balancing act providing sufficient cholestrol to confer stability but without making the membrane too restrictive to receptor activation. Within a given disk membrane, it is likely that cholesterol exhibits an asymmetric distribution between the inner and outer bilayer leaflets. Furthremore, there is some evidence of cholesterol microdomains in the disk membranes. The availability of the disk protein, rom-1 may be sensitive to membrane cholesterol. The effects exerted by cholesterol on rhodopsin function have far-reaching implications for the study of G-protein coupled receptors as a whole. These studies show that the function of a membrane receptor can be modulated by modification of HHS Public Access Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript the lipid bilayer, particularly cholesterol. This provides a powerful means of fine-tuning the activity of a membrane protein without resorting ...

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“…Even with so much new information, the connection between events of cell biology and particular lipid compositions-a kind of "lipid role assignment"-can be made in but a few cases. These exceptions include the phosphoinositide binding of particular proteins to the plasma membrane inner leaflet (McLaughlin and Murray 2005) and polyunsaturated acyl chains of lipids in the retinal rod, which are needed for full activity of rhodopsin (Polozova and Litman 2000). More information is known about plasma membranes than about any other cell membranes, making the plasma membrane a starting point for thinking about lipid roles in mammalian cell membranes.…”

Section: Lipids Found In Cell Membranesmentioning

confidence: 99%

Phase Separation in Lipid Membranes

Heberle¹,

Feigenson²

2011

Cold Spring Harbor Perspectives in Biology

215

180

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Cell membranes show complex behavior, in part because of the large number of different components that interact with each other in different ways. One aspect of this complex behavior is lateral organization of components on a range of spatial scales. We found that lipidonly mixtures can model the range of size scales, from approximately 2 nm up to microns. Furthermore, the size of compositional heterogeneities can be controlled entirely by lipid composition for mixtures such as 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)/1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/cholesterol or sphingomyelin (SM)/DOPC/POPC/cholesterol. In one region of special interest, because of its connection to cell membrane rafts, nanometer-scale domains of liquid-disordered phase and liquid-ordered phase coexist over a wide range of compositions. SCALES OF SPATIAL ORGANIZATION OF CELL MEMBRANESC ell membranes have daunting complexity, including but not limited to the scales of spatial organization that emerge from a complex system. Complex behavior arises in part from the large number of different kinds of lipids and proteins, the different ways in which these membrane components interact with each other and with the rest of the cell, and the dynamic processes that locally and dramatically change significant fractions of the membrane. To appreciate the nature of this behavior, various key aspects of the complexity must be examined. Although a complete picture has not yet emerged, the available data are compelling that compositional heterogeneity, rather than random mixing of membrane lipids and proteins, describes cell membranes (Lingwood and Simons 2010). Here, we focus on one specific subset of complex membrane behavior: lateral heterogeneity based on lipid -lipid interactions in multicomponent bilayer mixtures. The impetus for examining such mixtures is the apparent connection between the coexistence of liquiddisordered (Ld) and liquid-ordered (Lo) phases observed in some simple, lipid-only bilayers, and the properties of lipid rafts observed in some cellular membranes. One possible starting point for experimental study is to find the simplest system that shows a wide range of organization comparable to what is found in cells, that is, from nanometers to microns. This turns out

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Cholesterol Dependent Recruitment of di22:6-PC by a G Protein-Coupled Receptor into Lateral Domains

Cited by 116 publications

References 51 publications

Association of a Photoreceptor-specific Tetraspanin Protein, ROM-1, with Triton X-100-resistant Membrane Rafts from Rod Outer Segment Disk Membranes

Association of a Photoreceptor-specific Tetraspanin Protein, ROM-1, with Triton X-100-resistant Membrane Rafts from Rod Outer Segment Disk Membranes

The role of cholesterol in rod outer segment membranes

Phase Separation in Lipid Membranes

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