FABP4 Antibody [H23L13] | Primary Antibodies

Application: Reactivity: Human, Mouse, Rat

Lane 1: Mouse brown adipose, Lane 2: Rat brown adipose

Experiment Essentials

WB
Recommended SDS-PAGE separating gel concentration: 20%.
Recommended wet transfer conditions: 200 mA, 60 min，Recommended to use 0.22 μm PVDF membrane.

Usage Information

Dilution
WB1:1000

Application
WB

Reactivity
Human, Mouse, Rat

Source
Rabbit Monoclonal Antibody

Storage Buffer
PBS, pH 7.2+50% Glycerol+0.05% BSA+0.01% NaN3

Storage (from the date of receipt)
-20°C (avoid freeze-thaw cycles), 2 years

Predicted MW
15 kDa

Positive Control	Mouse brown adipose tissue; Rat brown adipose tissue; RT-4 cells
Negative Control	U-2 OS cells

Experimental Methods

WB
Experimental Protocol: Sample preparation 1. Tissue: Lyse the tissue sample by adding an appropriate volume of ice-cold RIPA/NP-40 Lysis Buffer (containing Protease Inhibitor Cocktail)，and homogenize the tissue at a low temperature. 2. Adherent cell: Aspirate the culture medium and wash the cells with ice-cold PBS twice. Lyse the cells by adding an appropriate volume of RIPA/NP-40 Lysis Buffer (containing Protease Inhibitor Cocktail) and put the sample on ice for 5 min. 3. Suspension cell: Transfer the culture medium to a pre-cooled centrifuge tube. Centrifuge and aspirate the supernatant. Wash the cells with ice-cold PBS twice. Lyse the cells by adding an appropriate volume of RIPA/NP-40 Lysis Buffer (containing Protease Inhibitor Cocktail) and put the sample on ice for 5 min. 4. Place the lysate into a pre-cooled microcentrifuge tube. Centrifuge at 4°C for 15 min. Collect the supernatant; 5. Remove a small volume of lysate to determine the protein concentration; 6. Combine the lysate with protein loading buffer. Boil 20 µL sample under 95-100°C for 5 min. Centrifuge for 5 min after cool down on ice. Electrophoretic separation 1. According to the concentration of extracted protein, load appropriate amount of protein sample and marker onto SDS-PAGE gels for electrophoresis. Recommended separating gel (lower gel) concentration: 20%. Reference Table for Selecting SDS-PAGE Separation Gel Concentrations 2. Power up 80V for 30 minutes. Then the power supply is adjusted (110 V~150 V), the Marker is observed, and the electrophoresis can be stopped when the indicator band of the predyed protein Marker where the protein is located is properly separated. (Note that the current should not be too large when electrophoresis, too large current (more than 150 mA) will cause the temperature to rise, affecting the result of running glue. If high currents cannot be avoided, an ice bath can be used to cool the bath.) Transfer membrane 1. Take out the converter, soak the clip and consumables in the pre-cooled converter; 2. Activate PVDF membrane with methanol for 1 min and rinse with transfer buffer; 3. Install it in the order of "black edge of clip - sponge - filter paper - filter paper - glue -PVDF membrane - filter paper - filter paper - sponge - white edge of clip"; 4. The protein was electrotransferred to PVDF membrane. ( 0.22 µm PVDF membrane is recommended )） Reference Table for Selecting PVDF Membrane Pore Size Specifications Recommended conditions for wet transfer: 200 mA, 60 min. ( Note that the transfer conditions can be adjusted according to the protein size. For high-molecular-weight proteins, a higher current and longer transfer time are recommended. However, ensure that the transfer tank remains at a low temperature to prevent gel melting.) Block 1. After electrotransfer, wash the film with TBST at room temperature for 5 minutes; 2. Incubate the film in the blocking solution for 1 hour at room temperature; 3. Wash the film with TBST for 3 times, 5 minutes each time. Antibody incubation 1. Use 5% skim milk powder to prepare the primary antibody working liquid (recommended dilution ratio for primary antibody 1:1000), gently shake and incubate with the film at 4°C overnight; 2. Wash the film with TBST 3 times, 5 minutes each time; 3. Add the secondary antibody to the blocking solution and incubate with the film gently at room temperature for 1 hour; 4. After incubation, wash the film with TBST 3 times for 5 minutes each time. Antibody staining 1. Add the prepared ECL luminescent substrate (or select other color developing substrate according to the second antibody) and mix evenly; 2. Incubate with the film for 1 minute, remove excess substrate (keep the film moist), wrap with plastic film, and expose in the imaging system.

WB

Experimental Protocol:

Sample preparation

1. Tissue: Lyse the tissue sample by adding an appropriate volume of ice-cold RIPA/NP-40 Lysis Buffer (containing Protease Inhibitor Cocktail)，and homogenize the tissue at a low temperature.

2. Adherent cell: Aspirate the culture medium and wash the cells with ice-cold PBS twice. Lyse the cells by adding an appropriate volume of RIPA/NP-40 Lysis Buffer (containing Protease Inhibitor Cocktail) and put the sample on ice for 5 min.

3. Suspension cell: Transfer the culture medium to a pre-cooled centrifuge tube. Centrifuge and aspirate the supernatant. Wash the cells with ice-cold PBS twice. Lyse the cells by adding an appropriate volume of RIPA/NP-40 Lysis Buffer (containing Protease Inhibitor Cocktail) and put the sample on ice for 5 min.

4. Place the lysate into a pre-cooled microcentrifuge tube. Centrifuge at 4°C for 15 min. Collect the supernatant;

5. Remove a small volume of lysate to determine the protein concentration;

6. Combine the lysate with protein loading buffer. Boil 20 µL sample under 95-100°C for 5 min. Centrifuge for 5 min after cool down on ice.

Electrophoretic separation

1. According to the concentration of extracted protein, load appropriate amount of protein sample and marker onto SDS-PAGE gels for electrophoresis. Recommended separating gel (lower gel) concentration: 20%. Reference Table for Selecting SDS-PAGE Separation Gel Concentrations

2. Power up 80V for 30 minutes. Then the power supply is adjusted (110 V~150 V), the Marker is observed, and the electrophoresis can be stopped when the indicator band of the predyed protein Marker where the protein is located is properly separated. (Note that the current should not be too large when electrophoresis, too large current (more than 150 mA) will cause the temperature to rise, affecting the result of running glue. If high currents cannot be avoided, an ice bath can be used to cool the bath.)

Transfer membrane

1. Take out the converter, soak the clip and consumables in the pre-cooled converter;

2. Activate PVDF membrane with methanol for 1 min and rinse with transfer buffer;

3. Install it in the order of "black edge of clip - sponge - filter paper - filter paper - glue -PVDF membrane - filter paper - filter paper - sponge - white edge of clip";

4. The protein was electrotransferred to PVDF membrane. ( 0.22 µm PVDF membrane is recommended )） Reference Table for Selecting PVDF Membrane Pore Size Specifications

Recommended conditions for wet transfer: 200 mA, 60 min.

( Note that the transfer conditions can be adjusted according to the protein size. For high-molecular-weight proteins, a higher current and longer transfer time are recommended. However, ensure that the transfer tank remains at a low temperature to prevent gel melting.)

Block

1. After electrotransfer, wash the film with TBST at room temperature for 5 minutes;

2. Incubate the film in the blocking solution for 1 hour at room temperature;

3. Wash the film with TBST for 3 times, 5 minutes each time.

Antibody incubation

1. Use 5% skim milk powder to prepare the primary antibody working liquid (recommended dilution ratio for primary antibody 1:1000), gently shake and incubate with the film at 4°C overnight;

2. Wash the film with TBST 3 times, 5 minutes each time;

3. Add the secondary antibody to the blocking solution and incubate with the film gently at room temperature for 1 hour;

4. After incubation, wash the film with TBST 3 times for 5 minutes each time.

Antibody staining

1. Add the prepared ECL luminescent substrate (or select other color developing substrate according to the second antibody) and mix evenly;

2. Incubate with the film for 1 minute, remove excess substrate (keep the film moist), wrap with plastic film, and expose in the imaging system.

Datasheet & SDS

Biological Description

Specificity
FABP4 Antibody [H23L13] detects endogenous levels of total FABP4 protein.

Subcellular Location
Cytoplasm, Nucleus

Uniprot ID
P15090

Clone
H23L13

Synonym(s)
Fatty acid-binding protein, adipocyte;Adipocyte lipid-binding protein (ALBP);Adipocyte-type fatty acid-binding protein (A-FABP; AFABP);Fatty acid-binding protein 4;FABP4

Background
Fatty acid–binding protein 4 (FABP4), also known as adipocyte fatty acid–binding protein (A‑FABP or aP2), is a small cytoplasmic lipid chaperone of the FABP family that is predominantly expressed in adipocytes and macrophages and functions as a major intracellular carrier of long‑chain fatty acids and other hydrophobic ligands. The protein binds fatty acids with high affinity, shuttles them between membranes and enzymes, and modulates the availability of lipid species for metabolic, signaling, and inflammatory pathways, including lipolysis‑driven release, β‑oxidation, and eicosanoid production. FABP4 influences PPARγ activity and adipogenic gene programs, and in macrophages it contributes to lipid‑handling and proinflammatory activation, thereby linking lipid trafficking to both metabolic regulation and low‑grade inflammation (“metaflammation”). Mouse models lacking FABP4 show increased obesity on high‑fat diets yet remain protected from insulin resistance and diabetes, and FABP4‑deficient mice also exhibit reduced atherosclerosis when crossed with ApoE‑null backgrounds, indicating that FABP4 couples obesity to insulin resistance and vascular disease. Low‑expression variant in the FABP4 promoter associates with reduced risk of type 2 diabetes and coronary heart disease, and circulating FABP4 levels correlate with insulin resistance, metabolic syndrome, and cardiovascular events, acting as a systemic biomarker and effector.

Background

Fatty acid–binding protein 4 (FABP4), also known as adipocyte fatty acid–binding protein (A‑FABP or aP2), is a small cytoplasmic lipid chaperone of the FABP family that is predominantly expressed in adipocytes and macrophages and functions as a major intracellular carrier of long‑chain fatty acids and other hydrophobic ligands. The protein binds fatty acids with high affinity, shuttles them between membranes and enzymes, and modulates the availability of lipid species for metabolic, signaling, and inflammatory pathways, including lipolysis‑driven release, β‑oxidation, and eicosanoid production. FABP4 influences PPARγ activity and adipogenic gene programs, and in macrophages it contributes to lipid‑handling and proinflammatory activation, thereby linking lipid trafficking to both metabolic regulation and low‑grade inflammation (“metaflammation”). Mouse models lacking FABP4 show increased obesity on high‑fat diets yet remain protected from insulin resistance and diabetes, and FABP4‑deficient mice also exhibit reduced atherosclerosis when crossed with ApoE‑null backgrounds, indicating that FABP4 couples obesity to insulin resistance and vascular disease. Low‑expression variant in the FABP4 promoter associates with reduced risk of type 2 diabetes and coronary heart disease, and circulating FABP4 levels correlate with insulin resistance, metabolic syndrome, and cardiovascular events, acting as a systemic biomarker and effector.

References
https://pubmed.ncbi.nlm.nih.gov/30726793/ https://pubmed.ncbi.nlm.nih.gov/34244239/

Protein Size (kDa)	PVDF Transfer Membrane Pore Size (μm)
< 10	0.22
10-20	0.22
20-30	0.45
30-45	0.45
45-70	0.45
80-100	0.45
100-140	0.45
> 140	0.45

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Protein Size (kDa)	Separating Gel Percentage
4-40	20%
12-45	15%
10-70	12.5%
15-100	10%
25-100	8%
60-210	5%