1.5M Tris-HCl Buffer, pH 8.8

Membrane protein extraction with detergents and chaotropes solubilizes lipid-bilayer-associated proteins by disrupting protein-lipid and protein-protein interactions while maintaining proteins in a soluble state for downstream electrophoresis, purification, or mass spectrometry. Chaotropes such as urea and thiourea improve solubilization of difficult proteins, while nonionic and zwitterionic detergents such as CHAPS, ASB-14, SB 3-10, MEGA-10, dodecyl maltoside, and Triton X-100 differ in extraction efficiency depending on sample type and membrane protein properties.

Protein extraction uses physical, chemical or biological methods, such as ultrasonic disruption, salting out, cell lysis, electrophoresis, etc., to destroy the cell membrane structure and to separate the proteins from different components according to their characteristics.

Detergent-based total protein extraction lyses cultured mammalian cells by using amphipathic detergents to disrupt lipid membranes and solubilize proteins into aqueous lysate; RIPA combines non-ionic detergent with ionic detergents, whereas NP-40/Triton buffers are milder non-ionic lysis conditions. The readout is the recovered clarified protein lysate, which is commonly quantified by detergent-compatible protein assays and then used for downstream protein analysis such as SDS-PAGE and Western blotting.

Gel electrophoresis is a method for separating biological macromolecules (such as nucleic acids or proteins) by forcing them through a gel matrix under an electric field.

Protein electrophoresis separates proteins in a polyacrylamide gel under an electric field; in SDS-PAGE, sodium dodecyl sulfate denatures proteins and gives them a broadly similar negative charge-to-mass ratio, so migration mainly reflects apparent molecular mass through the gel matrix. The readout is a stained protein band pattern: band position estimates apparent molecular mass using protein standards, band intensity reflects relative protein abundance within the linear range of staining/detection, and changes in band pattern can reflect protein expression, degradation, purification, or sample composition.