INSTRUCTIONS 
 
 
 
 
 
 
 
 
 
 
 
 
      Pierce Biotechnology  PO Box 117  (815) 968-0747  www.thermoscientific。。ｃｏｍ/pierce 
      3747 N. Meridian Road  Rockford, lL 61105 USA  (815) 968-7316   
 
Number  Description 
89826   Mem-PER Eukaryotic Membrane Protein Extraction Reagent Kit, contains sufficient lysis and 
extraction reagents for approximay 50-100 mammalian cell pellet fractions containing 5 × 106
 cells 
each, 15mg of wet yeast cell paste, or 20mg of tissue 
 
  Kit Contents: 
  Mem-PER Reagent A, 10mL 
  Mem-PER Reagent B, 25mL 
  Mem-PER Reagent C, 40mL 
 
  Storage: Upon receipt store Reagent A at room temperature. Store Reagent B and Reagent C at 4°C. 
Product is shipped at ambient temperature. 
  Note: The ambient shipping conditions may cause Reagent C to appear cloudy upon receipt. Storage at 
4°C will clarify the solution. Keep Reagent C at 4°C or on ice at all times. 
 
Table of Contents 
Introduction .................................................................................................................................................................................  1 
Important Product Information  ....................................................................................................................................................  2 
Additional Material Required  ......................................................................................................................................................  2 
Procedure for Membrane Protein Extraction from Different Sample Types ...............................................................................  2 
Protocol 1: Mammalian Cells ..................................................................................................................................................  2 
Protocol 2: Yeast Cells ............................................................................................................................................................  3 
Protocol 3: Soft Tissue  .............................................................................................................................................................  3 
Protocol 4: Hard Tissue ...........................................................................................................................................................  4 
Procedure for Performing a Second Extraction ...........................................................................................................................  4 
Preparation of Samples for Downstream Applications  ................................................................................................................  5 
A.  SDS Polyacrylamide Gel Electrophoresis (PAGE) ........................................................................................................  5 
B.  Protein Quantitation  ........................................................................................................................................................  5 
C.  Other Applications  ..........................................................................................................................................................  5 
Additional Information  ................................................................................................................................................................  5 
Related Thermo Scientific Products ............................................................................................................................................  6 
 
Introduction 
The Thermo Scientific Mem-PER Eukaryotic Membrane Protein Extraction Reagent Kit is for the enrichment of integral 
membrane proteins from cultured mammalian or yeast cells or from mammalian tissue using a mild detergent-based protocol. 
The cells are first lysed with a detergent, after which a second detergent is added to solubilize the membrane proteins. The 
cocktail is incubated at 37°C to separate the hydrophobic proteins from the hydrophilic proteins through phase partitioning. 
Extraction efficiencies will vary depending on the number of times the integral membrane protein(s) of interest spans the 
lipid bilayer. Membrane proteins with up to four transmembrane domains are typically extracted with an efficiency of up to 
90%. Cross-contamination of cytosolic proteins into the membrane fraction is typically < 10%. 
 
1312.11 
 
89826 
 
Mem-PER? Eukaryotic Membrane 
Protein Extraction Reagent Kit 
  
 
 
 
 
 
      Pierce Biotechnology  PO Box 117  (815) 968-0747  www.thermoscientific。。ｃｏｍ/pierce 
      3747 N. Meridian Road  Rockford, lL 61105 USA  (815) 968-7316   
 
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Important Product Information 
?  For optimal results, include protease inhibitors (e.g., Product No. 78415) in the Mem-PER Reagents. 
?  Perform 37°C incubation step in a water bath. Incubator ovens do not heat evenly enough for this application. 
?  Do not exceed 10 samples in one extraction procedure because rapid resolubilization of the hydrophobic phase into the 
hydrophilic phase occurs at room temperature. 
?  For downstream processing of samples, refer to the Preparation of Samples for Downstream Applications Section 
following the main protocols. 
 
Additional Material Required 
?  Protease inhibitors (e.g., Product No. 78415) 
?  For soft tissues, a 2mL Dounce Tissue Grinder, such as Kontes or Wheaton Tenbroeck, is required.  
?  For hard tissues a hand-held homogenizer for 0.5 to 1.5mL samples, such as the Brinkmann Polytron PT-1200CL, is 
required. 
?  Tris Buffered Saline (TBS; 0.025M Tris, 0.15M NaCl; pH 7.2; Product No. 28376) containing protease inhibitors 
?  Water bath equilibrated to 37°C. Do not use an incubator oven, which will not heat evenly enough for this application. 
 
Procedure for Membrane Protein Extraction from Different Sample Types 
Following are four protocols: Protocol 1 is for the extraction of membrane proteins from mammalian cells; Protocol 2 is for 
the extraction of membrane proteins from yeast cells: Protocol 3 is for the extraction of membrane proteins from soft tissues; 
and Protocol 4 is for the extraction of membrane proteins from hard tissues. (See the Additional Information Section for a 
schematic of the mammalian cells and tissue protocols.) 
Note: Additional protein recovery may be recovered with a second extraction; see protocol at the end of this section. 
Protocol 1: Mammalian Cells 
1.  Isolate 5 × 106
 cells per sample by centrifuging harvested cell suspensions at 850 × g for 2 minutes. Pellet cells (washed 
in PBS) in 1.7mL microcentrifuge tubes. 
2.  Carefully remove and discard the supernatant. 
3.  Add 150μL of Reagent A to the cell pellet. Pipette up and down to obtain a homogeneous cell suspension. Incubate 10 
minutes at room temperature with occasional vortexing.  
Note: White, flocculent debris appears upon addition of Reagent A. 
Note: To check the cell lysis efficiency, spot 5μL of cell lysate onto a glass slide, add coverslip and view under a light 
microscope. Compare with 5μL of the same number of intact cells in 150μL of phosphate-buffered saline (PBS) or Tris-
buffered saline (TBS). 
4.  Place lysed cells on ice. 
5.  Dilute 2 parts Reagent C with 1 part Reagent B, making sufficient mixture for each sample to receive 450μL (e.g., for 10 
extractions, combine 3.33mL of Reagent C with 1.67mL of Reagent B). Keep Reagents B and C at 4°C or on ice at all 
times. 
6.  Add 450μL of diluted Reagent C to each tube of lysed cells and vortex. Incubate tubes on ice for 30 minutes, vortexing 
every 5 minutes. 
7.  Centrifuge tubes at 10,000 × g for 3 minutes at 4°C. Transfer supernatant to new tubes and incubate 10 minutes in 37°C 
water bath to separate the membrane protein fraction. To enhance phase separation, increase incubation to 20 minutes.  
8.  Centrifuge tubes at room temperature for 2 minutes at 10,000 × g to isolate the hydrophobic fraction (i.e., the fraction 
containing membrane protein of interest) from the hydrophilic fraction.  
 
 
 
 
 
      Pierce Biotechnology  PO Box 117  (815) 968-0747  www.thermoscientific。。ｃｏｍ/pierce 
      3747 N. Meridian Road  Rockford, lL 61105 USA  (815) 968-7316   
 
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9.  Carefully remove the hydrophilic phase (top layer) from the hydrophobic protein phase (bottom layer) and save in a new 
tube. Perform phase separations as quickly as possible because the interface between the layers slowly disappears at 
room temperature.  
10.  Place the separated fractions on ice. The majority of membrane protein will be in the lower hydrophobic fraction, which 
can be used for membrane protein analysis.  
 
Protocol 2: Yeast Cells 
1.  Prepare approximay 150mg of 405-600μm acid-washed glass beads 
2.  Harvest yeast cells in the exponential growth phase at a density of 1-5 × 107
 cells/mL with an OD600 = 0.3-1.7. Use 
approximay, 15mg of wet cell paste per assay. 
3.  Pellet cells by pulse centrifugation and carefully remove the supernatant. 
4.  Resuspend cells in 80μL of Reagent A. Pipette up and down to obtain a homogeneous cell suspension. 
5.  Add the acid-washed glass beads to the cell suspension and vortex for 10 minutes to lyse cells. Pellet the beads by pulse 
centrifugation. Transfer the cell suspension into a new microcentrifuge tube and keep on ice. 
6.  Dilute 2 parts Reagent C with 1 part Reagent B, making sufficient mixture for each sample to receive 720μL (e.g., for 10 
extractions, combine 4.8mL of Reagent C with 2.4mL of Reagent B). Keep Reagents B and C at 4°C or on ice at all 
times. 
7.  Add 720μL of diluted Reagent C into the tube containing the glass beads and briefly vortex to wash. Perform a pulse 
spin to gather beads. 
8.  Transfer wash into tube containing the cell suspension and incubate on ice for 30 minutes, vortexing every five minutes. 
9.  Centrifuge at 10,000 × g for three minutes at 4°C. Transfer supernatant to new tubes and incubate 10 minutes in 37°C 
water bath to separate the membrane protein fraction. To enhance phase separation, increase incubation to 20 minutes. 
10.  Centrifuge tubes at room temperature (RT) for two minutes at 10,000 × g to isolate the hydrophobic fraction (i.e., the 
fraction containing the membrane protein of interest) from the hydrophilic fraction. 
11.  Carefully remove hydrophilic phase (top layer) from the hydrophobic phase (bottom layer) and save in a new tube. 
Perform phase separations as quickly as possible because the interface between layers slowly disappears at RT.  
12.  Place the separated fractions on ice. The majority of membrane proteins will be in the lower hydrophobic fraction, which 
can be used for membrane protein analysis. 
 
Protocol 3: Soft Tissue  
1.  Place 20mg of soft tissue in a 1.5mL microcentrifuge tube. Add 200μL of TBS to tissue, vortex briefly and discard wash.  
2.  Transfer rinsed tissue to a 2mL tissue grinder. Add 200μL of TBS to the tissue and homogenize until an even suspension 
is obtained (~6 to 10 strokes). 
3.  Transfer homogenate to a new 1.5mL tube and centrifuge at 1000 × g for 5 minutes at 4°C. 
4.  Discard supernatant and resuspend the pellet in 150μL of Reagent A. Pipette up and down to obtain a homogeneous 
suspension. Incubate 10 minutes at room temperature with occasional vortexing.  
Note: White, flocculent debris appears upon addition of Reagent A. 
5.  Place lysed cells on ice. 
6.  Dilute 2 parts Reagent C with 1 part Reagent B, making sufficient mixture for each sample to receive 450μL (e.g., for 10 
extractions, combine 3.33mL of Reagent C with 1.67mL of Reagent B). Keep Reagents B and C at 4°C or on ice at all 
times. 
7.  Add 450μL of diluted Reagent C to each tube of lysed cells and vortex. Incubate tubes on ice for 30 minutes, vortexing 
every 5 minutes. 
8.  Centrifuge tubes at 10,000 × g for 3 minutes at 4°C. Transfer supernatant to new tubes and incubate 10 minutes in 37°C 
water bath to separate the membrane protein fraction. To enhance phase separation, increase incubation to 20 minutes.  
 
 
 
 
 
      Pierce Biotechnology  PO Box 117  (815) 968-0747  www.thermoscientific。。ｃｏｍ/pierce 
      3747 N. Meridian Road  Rockford, lL 61105 USA  (815) 968-7316   
 
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9.  Centrifuge tubes at room temperature (RT) for 2 minutes at 10,000 × g to isolate the hydrophobic fraction (i.e., the 
fraction containing membrane protein of interest) from the hydrophilic fraction. 
10.  Carefully remove hydrophilic phase (top layer) from the hydrophobic protein phase (bottom layer) and save in a new 
tube. Perform phase separations as quickly as possible because the interface between layers slowly disappears at RT.  
11.  Place the separated fractions on ice. The majority of membrane protein will be in the lower hydrophobic fraction, which 
can be used for membrane protein analysis.  
 
Protocol 4: Hard Tissue 
1.  Place 20mg of hard tissue in a 2.0mL microcentrifuge tube. Add 500μL of TBS to the tissue, vortex briefly and discard 
the wash.  
2.  Add 500μL of TBS to the tissue and cut the tissue into small pieces with a clean razor blade. 
3.  Homogenize minced tissue with a hand-held Polytron?, using a low setting to prevent foaming. Transfer homogenate to 
a new 1.5mL tube and centrifuge at 1000 × g for 5 minutes at 4°C. 
4.  Discard the supernatant and resuspend the pellet in 150μL Reagent A. Pipette up and down to obtain a homogeneous 
suspension. Incubate 10 minutes at room temperature with occasional vortexing.  
Note: White, flocculent debris appears upon addition of Reagent A. 
5.  Place lysed cells on ice. 
6.  Dilute 2 parts Reagent C with 1 part Reagent B, making sufficient mixture for each sample to receive 450μL (e.g., for 10 
extractions, combine 3.33mL of Reagent C with 1.67mL of Reagent B). Keep Reagents B and C at 4°C or on ice at all 
times. 
7.  Add 450μL of diluted Reagent C to each tube of lysed cells and vortex. Incubate tubes on ice for 30 minutes, vortexing 
every 5 minutes. 
8.  Centrifuge tubes at 10,000 × g for 3 minutes at 4°C. Transfer supernatant to new tubes and incubate 10 minutes in 37°C 
water bath to separate the membrane protein fraction. To enhance phase separation, increase incubation to 20 minutes. 
9.  Centrifuge tubes at room temperature for 2 minutes at 10,000 × g to isolate the hydrophobic fraction (i.e., the fraction 
containing membrane protein of interest) from the hydrophilic fraction. 
10.  Carefully remove the hydrophilic phase (top layer) from the hydrophobic protein phase (bottom layer) and save in a new 
tube. Perform the phase separations as quickly as possible because the interface between the layers slowly disappears at 
room temperature.  
11.  Place the separated fractions on ice. The majority of membrane protein will be in the lower hydrophobic fraction, which 
can be used for membrane protein(s) analysis.  
 
Procedure for Performing a Second Extraction 
Although typically not necessary, a second extraction may result in additional protein recovery. 
1.  Determine volume of the hydrophilic fraction and add an equal volume of undiluted Reagent C to this fraction and 
vortex. 
2.  Incubate tubes on ice for 30 minutes, vortexing every 5 minutes during the incubation. 
3.  Incubate tubes for 10 minutes in a 37°C water bath to separate the membrane protein fraction. To enhance phase 
separation, increase incubation to 20 minutes. 
4.  Centrifuge tubes at room temperature for 2 minutes at 10,000 × g to isolate the hydrophobic fraction from the 
hydrophilic fraction. 
5.  Carefully remove the hydrophilic phase (top layer) from the hydrophobic protein phase (bottom layer) and save in a new 
tube. Perform phase separations as quickly as possible because the interface between layers slowly disappears at room 
temperature. Place separated fractions on ice. 
6.  Combine hydrophobic fraction from the first extraction with the hydrophobic fraction from the second extraction. 
  
 
 
 
 
 
      Pierce Biotechnology  PO Box 117  (815) 968-0747  www.thermoscientific。。ｃｏｍ/pierce 
      3747 N. Meridian Road  Rockford, lL 61105 USA  (815) 968-7316   
 
5 
Preparation of Samples for Downstream Applications  
A.  SDS Polyacrylamide Gel Electrophoresis (PAGE)  
To determine extraction efficiency, perform SDS-PAGE and identify the protein(s) of interest by Western blotting. Dilute 
membrane fractions 2- to 5-fold to prevent band and lane distortion caused by high concentrations of detergent. Use Reagent 
B diluted 4-fold with ultrapure water for dilution and/or normalization. Alternatively, use the Thermo Scientific Pierce SDS-
PAGE Sample Prep Kit (Product No. 89888) to decrease detergent in the membrane fraction. Use this kit if the protein of 
interest is in low abundance and a large volume is required for adequate detection; for samples prepared using two 
extractions; or for proteins that migrate at or near the dye front because migrating detergent at the same location causes 
severe band distortion.  
B.  Protein Quantitation  
To directly quantify proteins in the hydrophilic fraction, use a protein assay, such as the Pierce
? BCA Protein Assay 
(Product No. 23225), Micro BCA? Protein Assay (Product No. 23235), Coomassie Plus (Bradford) Protein Assay (Product 
No. 23236) or Pierce 660nm Protein Assay (Product No. 22660).  
To quantify proteins in the hydrophobic fraction, first decrease detergent in the membrane fraction to prevent interference. If 
performing subsequent SDS-PAGE, we recommend using the Pierce SDS-PAGE Sample Prep Kit (Product No. 89888) 
followed directly by the Pierce BCA Protein Assay Kit. If performing applications other than SDS-PAGE after quantitation, 
see Section C below. 
C.  Other Applications 
 If the hydrophobic fraction requires decreased detergent for other applications, such as functional studies, 
immunoprecipitation or quantitation, an alternative option is to use Pierce Detergent Removal Spin Columns (Product No. 
87776-7). The sample:resin ratio will need to be determined empirically: If too little detergent is removed, the remaining 
detergent may interfere with the downstream application. If too much detergent is removed, protein precipitation may occur. 
 
Additional Information 
Mem-PER Eukaryotic Membrane Protein Extraction Reagent Kit is for the enrichment of integral membrane proteins using a 
mild detergent-based protocol. For mammalian cells, a detergent is used to first lyse cells, and then a second detergent is 
added to solubilize the membrane proteins. The cocktail is incubated at 37°C to separate the hydrophobic proteins from the 
hydrophilic proteins through phase partitioning (Figure 1). Yeast cells require the use of acid-washed glass beads for cell 
disruption. Hard and soft tissues also require mechanical means for disruption (Figure 2). 
 
 
 
Figure 1. Summary of membrane protein extraction from mammalian cells. 
  
 
 
 
 
 
      Pierce Biotechnology  PO Box 117  (815) 968-0747  www.thermoscientific。。ｃｏｍ/pierce 
      3747 N. Meridian Road  Rockford, lL 61105 USA  (815) 968-7316   
 
6 
 
Figure 2. Summary of membrane protein extraction from soft and hard tissues. 
 
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