Cubilin C-terminal Antibody [C16H20]

Application: Reactivity: Human

Immunohistochemical analysis of formalin fixed paraffin embedded huamn kidney tissue with F3474 at 1:10000 dilution.

Experiment Essentials

WB
Recommended SDS-PAGE separating gel concentration: 5%.
Recommended wet transfer conditions: 250 mA, 180 min.
Recommended WB dilution ratio: 1:10000

Usage Information

Dilution
WB1:10000 - 1:50000 IHC1:500

Application
WB, IHC

Reactivity
Human

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 Observed MW
399 kDa 399 kDa
^*Why do the predicted and actual molecular weights differ? The following reasons may explain differences between the predicted and actual protein molecular weight. Post-translational modifications(e.g., phosphorylation, glycosylation); Splice variants and isoforms; Relative charge; Multimerization.

Positive Control	Human fetal kidney tissue; Human kidney tissue
Negative Control

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 or lyse it by sonication on ice, then incubate on ice for 30 minutes. 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) , sonicate to lyse the cells, and incubate on ice for 30 minutes. 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) , sonicate to lyse the cells, and incubate on ice for 30 minutes. 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: 5%. 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. ( 0.45 µm PVDF membrane is recommended ) Reference Table for Selecting PVDF Membrane Pore Size Specifications Recommended conditions for wet transfer: 250 mA, 180 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 1:10000), 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 or lyse it by sonication on ice, then incubate on ice for 30 minutes.

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) , sonicate to lyse the cells, and incubate on ice for 30 minutes.

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) , sonicate to lyse the cells, and incubate on ice for 30 minutes.

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: 5%. 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. ( 0.45 µm PVDF membrane is recommended ) Reference Table for Selecting PVDF Membrane Pore Size Specifications

Recommended conditions for wet transfer: 250 mA, 180 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 1:10000), 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.

IHC
Experimental Protocol： Deparaffinization/Rehydration 1. Deparaffinize/hydrate sections: 2. Incubate sections in three washes of xylene for 5 min each. 3. Incubate sections in two washes of 100% ethanol for 10 min each. 4. Incubate sections in two washes of 95% ethanol for 10 min each. 5. Wash sections two times in dH2O for 5 min each. 6.Antigen retrieval: For Citrate: Heat slides in a microwave submersed in 1X citrate unmasking solution until boiling is initiated; continue with 10 min at a sub-boiling temperature (95°-98°C). Cool slides on bench top for 30 min. Staining 1. Wash sections in dH2O three times for 5 min each. 2. Incubate sections in 3% hydrogen peroxide for 10 min. 3. Wash sections in dH2O two times for 5 min each. 4. Wash sections in wash buffer for 5 min. 5. Block each section with 100–400 µl of blocking solution for 1 hr at room temperature. 6. Remove blocking solution and add 100–400 µl primary antibody diluent in to each section. Incubate overnight at 4°C. 7. Remove antibody solution and wash sections with wash buffer three times for 5 min each. 8. Cover section with 1–3 drops HRPas needed. Incubate in a humidified chamber for 30 min at room temperature. 9. Wash sections three times with wash buffer for 5 min each. 10. Add DAB Chromogen Concentrate to DAB Diluent and mix well before use. 11. Apply 100–400 µl DAB to each section and monitor closely. 1–10 min generally provides an acceptable staining intensity. 12. Immerse slides in dH2O. 13. If desired, counterstain sections with hematoxylin. 14. Wash sections in dH2O two times for 5 min each. 15. Dehydrate sections: Incubate sections in 95% ethanol two times for 10 sec each; Repeat in 100% ethanol, incubating sections two times for 10 sec each; Repeat in xylene, incubating sections two times for 10 sec each. 16. Mount sections with coverslips and mounting medium.

IHC

Experimental Protocol：

Deparaffinization/Rehydration

1. Deparaffinize/hydrate sections:

2. Incubate sections in three washes of xylene for 5 min each.

3. Incubate sections in two washes of 100% ethanol for 10 min each.

4. Incubate sections in two washes of 95% ethanol for 10 min each.

5. Wash sections two times in dH2O for 5 min each.

6.Antigen retrieval: For Citrate: Heat slides in a microwave submersed in 1X citrate unmasking solution until boiling is initiated; continue with 10 min at a sub-boiling temperature (95°-98°C). Cool slides on bench top for 30 min.

Staining

1. Wash sections in dH2O three times for 5 min each.

2. Incubate sections in 3% hydrogen peroxide for 10 min.

3. Wash sections in dH2O two times for 5 min each.

4. Wash sections in wash buffer for 5 min.

5. Block each section with 100–400 µl of blocking solution for 1 hr at room temperature.

6. Remove blocking solution and add 100–400 µl primary antibody diluent in to each section. Incubate overnight at 4°C.

7. Remove antibody solution and wash sections with wash buffer three times for 5 min each.

8. Cover section with 1–3 drops HRPas needed. Incubate in a humidified chamber for 30 min at room temperature.

9. Wash sections three times with wash buffer for 5 min each.

10. Add DAB Chromogen Concentrate to DAB Diluent and mix well before use.

11. Apply 100–400 µl DAB to each section and monitor closely. 1–10 min generally provides an acceptable staining intensity.

12. Immerse slides in dH2O.

13. If desired, counterstain sections with hematoxylin.

14. Wash sections in dH2O two times for 5 min each.

15. Dehydrate sections: Incubate sections in 95% ethanol two times for 10 sec each; Repeat in 100% ethanol, incubating sections two times for 10 sec each; Repeat in xylene, incubating sections two times for 10 sec each.

16. Mount sections with coverslips and mounting medium.

Datasheet & SDS

Biological Description

Specificity
Cubilin C-terminal Antibody (Rabbit mAb) [C16H20] detects endogenous levels of C-terminal region of total Cubilin protein.

Subcellular Location
Cell membrane, Coated pit, Endosome, Lysosome, Membrane

Uniprot ID
O60494

Clone
C16H20

Synonym(s)
IFCR, CUBN, Cubilin, 460 kDa receptor, Intestinal intrinsic factor receptor, Intrinsic factor-cobalamin receptor, Intrinsic factor-vitamin B12 receptor

Background
Cubilin is a large multiligand endocytic receptor of the CUB‑domain–containing family that is expressed at the apical surface of absorptive epithelia in the small intestine, renal proximal tubule, visceral yolk sac, and placenta, where it partners with amnionless and megalin to mediate receptor‑driven uptake of carrier‑bound nutrients and filtered plasma proteins. The ectodomain is built from a series of EGF‑like modules followed by 27 CUB domains that form repeated Ca²⁺‑binding ligand‑interaction modules; the C‑terminal half of cubilin contains a large subset of these CUB domains and contributes substantially to ligand binding and receptor multivalency. Calcium‑coordinated CUB domains in this region bind the intrinsic factor–cobalamin complex, albumin, apolipoprotein A‑I, transferrin, hemoglobin, vitamin D–binding protein (GC), immunoglobulin light chains, and high‑density lipoprotein particles, and biochemical mapping indicates that discrete CUB‑domain clusters within the C‑terminal portion provide overlapping but distinct binding sites for IF–B12 and albumin, allowing simultaneous or competitive capture of these ligands at the brush border. Cubilin lacks a transmembrane segment and relies on its N‑terminal interaction with amnionless to form the cubam complex, which anchors the receptor in the membrane and couples ligand‑occupied cubilin to clathrin‑mediated endocytosis and downstream endosomal trafficking, while cooperation with megalin further expands ligand repertoires and endocytic capacity. The C‑terminal half of cubilin is critical for renal protein reabsorption, and human C‑terminal CUBN variants that alter surface expression or ligand binding associate with chronic isolated albuminuria in the presence of preserved glomerular filtration and normal renal function, with the region as a determinant of proximal tubular albumin uptake efficiency rather than glomerular barrier integrity.

Background

Cubilin is a large multiligand endocytic receptor of the CUB‑domain–containing family that is expressed at the apical surface of absorptive epithelia in the small intestine, renal proximal tubule, visceral yolk sac, and placenta, where it partners with amnionless and megalin to mediate receptor‑driven uptake of carrier‑bound nutrients and filtered plasma proteins. The ectodomain is built from a series of EGF‑like modules followed by 27 CUB domains that form repeated Ca²⁺‑binding ligand‑interaction modules; the C‑terminal half of cubilin contains a large subset of these CUB domains and contributes substantially to ligand binding and receptor multivalency. Calcium‑coordinated CUB domains in this region bind the intrinsic factor–cobalamin complex, albumin, apolipoprotein A‑I, transferrin, hemoglobin, vitamin D–binding protein (GC), immunoglobulin light chains, and high‑density lipoprotein particles, and biochemical mapping indicates that discrete CUB‑domain clusters within the C‑terminal portion provide overlapping but distinct binding sites for IF–B12 and albumin, allowing simultaneous or competitive capture of these ligands at the brush border. Cubilin lacks a transmembrane segment and relies on its N‑terminal interaction with amnionless to form the cubam complex, which anchors the receptor in the membrane and couples ligand‑occupied cubilin to clathrin‑mediated endocytosis and downstream endosomal trafficking, while cooperation with megalin further expands ligand repertoires and endocytic capacity. The C‑terminal half of cubilin is critical for renal protein reabsorption, and human C‑terminal CUBN variants that alter surface expression or ligand binding associate with chronic isolated albuminuria in the presence of preserved glomerular filtration and normal renal function, with the region as a determinant of proximal tubular albumin uptake efficiency rather than glomerular barrier integrity.

References
https://pubmed.ncbi.nlm.nih.gov/31613795/ https://pubmed.ncbi.nlm.nih.gov/23291372/

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%

Cubilin C-terminal Antibody (Rabbit mAb) [C16H20]