LIPOPARTICLE TECHNOLOGY

Application Notes

THE LIPOPARTICLE
Lipoparticles incorporate high concentrations of properly folded and oriented membrane proteins on their surface. GPCRs, ion channels, and other complex membrane proteins can be incorporated into Lipoparticles at concentrations of 50-200 pmol/mg, 10-100 fold greater than cells or membrane preparations. Because Lipoparticles are virus-like particles （VLPs） based on the natural retroviral budding process, they are uniform in diameter （~150 nm） and maintain the orientation of incorporated membrane proteins. Integral Molecular produces, purifies, and delivers custom Lipoparticles containing user specified membrane proteins for applications in antibody development and drug discovery.

MODIFIED LIPOPARTICLES
Integral Molecular offers biochemically modified Lipoparticles containing biotin tags and fluorophores to enable membrane proteins to be captured onto solid supports and visualized without disrupting the conformation of incorporated receptor targets. Modified Lipoparticles are suited for use in specialized antibody development applications including:

ADVANTAGES
Lipoparticles offer distinct advantages over traditional sources of membrane proteins such as whole cells or membrane preparations:

Incorporation of difficult membrane proteins
Lipoparticles can incorporate oligomeric and multispanning membrane proteins in their correct topology. Receptors that are toxic or poorly trafficked can also be incorporated into Lipoparticles.

High purity and high concentrations of membrane proteins
Lipoparticles provide a source of concentrated membrane proteins that are free of cytoplasmic proteins and misoriented proteins, improving assay sensitivity and the specificity of immune responses.

Convenient and consistent source of membrane proteins
Lipoparticles maintain membrane proteins in their native lipid environment, preserving protein conformation. Lipoparticles are shipped ready to use and are stable for months with refrigeration, thereby eliminating end-user preparation steps and reducing experimental variability.

LIPOPARTICLE STRUCTURE
The Lipoparticle structure is based on membrane-enveloped retroviruses. Non-infectious, retroviral virus-like particles （VLPs） are produced when the viral protein 'Gag' buds through the host cell membrane. The Gag protein forms a core which becomes enwrapped by the cell membrane. Once the membrane ‘pinches’ off, newly formed Lipoparticles diffuse away from the cell, carrying target membrane proteins with it. Since the lipid membrane surrounding the Lipoparticle is derived directly from the host cell membrane, the incorporated receptors remain correctly oriented in a native lipid environment. Lipoparticles contain no viral genome or Envelope protein, and are replication incompetent and non-infectious, rendering them safe to manipulate in a standard laboratory environment.

LIPOPARTICLE QUALITY CONTROL
At Integral Molecular, Lipoparticles undergo rigorous quality control before they are shipped. As a result, the Lipoparticles you receive are highly purified, homogeneous, and stable for nths to years. Maintaining

• Immunization
• Phage and yeast display
• Screening for and characterizing MAbs
• Ligand binding assays
• Probing cells and microarrays
• Biosensor binding kinetics

Application versatility
Lipoparticles can be used with conventional formats such as microplates and beads, but their small size, exceptional purity, and stability also make them amenable to formats that are otherwise difficult for membrane proteins, such as microfluidics, microarrays, and biosensors.