CCKBR Antibody

What is CCKBR and what are its key functions in the context of antibody research?

The cholecystokinin B receptor (CCKBR), also known as Gastrin Receptor, CCK2R, CCK-B, GASR, or gastrin/cholecystokinin type B receptor, is a G-protein coupled receptor (GPCR) that binds both gastrin and cholecystokinin (CCK). This receptor has a molecular weight of approximately 48.4-56 kDa and is expressed predominantly in the central nervous system and gastrointestinal tract .

CCKBR plays critical roles in multiple physiological processes:

• In the central nervous system: Modulation of anxiety, analgesia, arousal, and neuroleptic activity

• In the gastrointestinal tract: Regulation of gastric acid secretion

• In the motor cortex: Facilitation of motor skill learning

• In pain processing: Involvement in chronic neuropathic pain models

Understanding the cellular and molecular mechanisms of CCKBR is essential for research in neuroscience, gastroenterology, and pain medicine. CCKBR antibodies serve as valuable tools for detecting, localizing, and studying the receptor in various experimental contexts.

What epitope regions should researchers target when selecting CCKBR antibodies for specific applications?

Choosing the appropriate epitope is critical for successful CCKBR detection. Different experimental needs may require targeting specific regions of the receptor:

For extracellular domain targeting, antibodies against peptide sequences such as "CETPRIRGTGTRELE" (corresponding to amino acids 39-53 of mouse CCKBR) have shown effectiveness in immunohistochemical studies of brain and stomach tissues . For human CCKBR detection, some researchers have successfully used antibodies against the sequence "PVYTVVQPVGPRVLQCVHRWPSARVRQTWS" .

When selecting an antibody, researchers should consider the conservation of epitopes across species if cross-reactivity is desired.

What methodological considerations are critical for Western blot detection of CCKBR?

Western blot detection of CCKBR requires careful optimization due to several receptor-specific characteristics:

• Glycosylation effects: CCKBR is heavily glycosylated, which can affect its apparent molecular weight. Research indicates that deglycosylation steps prior to Western blot analysis may be necessary for accurate detection .

• Sample preparation:

  • For membrane proteins like CCKBR, use specialized lysis buffers containing mild detergents

  • Recommended protein loading: 7-10 μg for plasma samples

  • Include protease inhibitors to prevent degradation

• Observed molecular weights:

  • Expected theoretical weight: 48.4-56 kDa

  • Observed weights: Multiple bands at approximately 50 kDa and 64 kDa due to post-translational modifications

• Dilution optimization:

  • Typical working dilutions range from 1:500-1:1000

  • Always perform a dilution series to determine optimal antibody concentration

• Validation controls:

  • Use blocking peptides specific to the antibody's epitope

  • Include positive control samples (e.g., BxPC-3 cells, human stomach tissue, or SGC-7901 cells)

  • Consider CCKBR-specific knockdown controls using siRNA (e.g., sequences targeting CCKBR: 5′-UAUACGAGUAGUAGCACCAdTdT-3′ or 5′-CCGCCAAAGGAUGGAGUACdTdT-3′)

How can researchers optimize immunohistochemistry protocols for CCKBR detection?

Successful immunohistochemical detection of CCKBR requires careful attention to tissue preparation and staining conditions:

• Tissue preparation options:

  • Paraffin embedding: Requires antigen retrieval (recommended: citrate buffer pH 6.0, microwave for 15 minutes)

  • Frozen sections: Typically provides better epitope preservation for membrane proteins like CCKBR

  • Perfusion-fixed tissues: Optimal for brain tissue analysis

• Protocol optimization:

  • Primary antibody incubation: Overnight at 4°C at dilutions of 1:100-1:200 for most CCKBR antibodies

  • For stomach tissues: 1:100 dilution has shown effective staining of both parietal cells and chief cells

  • For brain sections: 1:200 dilution for hypothalamus and hippocampus studies

• Detection systems:

  • For fluorescent detection: Secondary antibodies such as goat anti-rabbit-AlexaFluor-488 have shown good results

  • For chromogenic detection: Super Sensitive Link-Label IHC Detection System or equivalent

• Expected cellular localization:

  • Stomach: Expression in both parietal cells and chief cells of the gastric mucosa

  • Hypothalamus: Immunoreactivity in neurons and along the wall of 3rd ventricle

  • Hippocampus: Staining in the granule layer and in interneurons

What are the current applications of CCKBR antibodies in neuroscience research?

CCKBR antibodies have become valuable tools in neuroscience research, particularly in the following areas:

• Pain mechanisms and modulation:

  • CCKBR is implicated in neuropathic pain with both nociceptive and emotional components

  • Studies show that blocking CCKBR can reduce hypersensitivity, anxiety, and depression-like behaviors in pain models

  • Researchers use antibodies to localize CCKBR in trigeminal ganglia primary cultures to study neuronal firing frequency

• Motor learning studies:

  • CCKBR antibodies help elucidate the role of cholecystokinin in motor skill acquisition

  • Research with C57BL/6 mice demonstrates that CCKBR antagonists inhibit motor learning ability

  • Immunohistochemistry with CCKBR antibodies reveals expression patterns in relevant neural circuits

• Anxiety and depression research:

  • CCKBR is involved in anxiety, stress, and panic responses

  • Studies show CCK-B selective antagonists enhance morphine analgesia while preventing tolerance

  • Antibodies help map CCKBR expression in brain regions involved in emotional processing

• Neuron-specific activity analysis:

  • Researchers use CCKBR antibodies to analyze neuronal activity patterns in layer 2/3 of the motor cortex

  • Combined with calcium imaging (GCaMP6s), these studies reveal how CCK signaling affects neuronal refinement during learning

How can researchers differentiate between CCKAR and CCKBR in experimental systems?

Distinguishing between the two CCK receptor subtypes (CCKAR and CCKBR) is crucial for accurate interpretation of experimental results:

• Antibody selection:

  • Use receptor-specific antibodies: For CCKAR, antibodies like CCK-AR (H-60) antibody (sc-33220)

  • For CCKBR/GR, antibodies like CCK-BR (4A5) antibody (sc-53522)

• Positive control tissue selection:

  • CCKAR: Gallbladder muscle layer component serves as an effective positive control

  • CCKBR/GR: Pancreatic islet cells provide reliable positive control tissue

• Pharmacological discrimination:

  • CCKBR antagonists (e.g., in the foramen rotundum inflammatory compression trigeminal infraorbital nerve model) can help confirm CCKBR-specific effects in functional studies

  • Selective agonists can differentiate receptor activation patterns

• Genetic approaches:

  • Cck−/− knockout models can be used alongside CCKBR antagonist studies to confirm receptor-specific effects

  • siRNA knockdown targeting CCKBR specifically (5′-UAUACGAGUAGUAGCACCAdTdT-3′) can provide additional validation

• Binding characteristics:

  • CCKBR has high affinity for both sulfated and nonsulfated CCK analogs

  • CCKAR shows higher specificity for sulfated forms

What approaches are recommended for validating CCKBR antibody specificity?

Rigorous validation of CCKBR antibodies is essential for reliable research outcomes:

• Peptide blocking experiments:

  • Pre-incubate antibody with its immunizing peptide (e.g., CCKBR blocking peptide #BLP-CR042)

  • Compare staining patterns with and without blocking peptide

  • Loss of signal confirms specificity for the target epitope

• Genetic validation:

  • Use CCKBR knockout models or siRNA knockdown

  • Recommended siRNA sequences: 5′-UAUACGAGUAGUAGCACCAdTdT-3′ or 5′-CCGCCAAAGGAUGGAGUACdTdT-3′

• Multiple antibody approach:

  • Use antibodies targeting different epitopes of CCKBR

  • Concordant results increase confidence in specificity

• Cross-reactivity testing:

  • Test antibody on tissues/cells known to lack CCKBR expression

  • Check for species cross-reactivity if using the antibody across different animal models

• Comparison with mRNA expression:

  • Correlate protein detection with mRNA expression data

  • Consider hybridization approaches to confirm expression patterns

What are the challenges in detecting post-translationally modified CCKBR?

Detection of CCKBR is complicated by several post-translational modifications:

• Glycosylation issues:

  • CCKBR is heavily glycosylated, affecting apparent molecular weight

  • Research strongly recommends deglycosylation steps prior to Western blot detection

  • Without deglycosylation, multiple bands or shifted bands may appear

• Alternative splicing detection:

  • A misspliced transcript variant including an intron has been observed in colorectal and pancreatic tumors

  • Different antibodies may have varying abilities to detect these variants

• Receptor internalization:

  • Upon ligand binding, CCKBR undergoes internalization

  • This affects surface vs. intracellular detection ratios

  • Kinase inhibitor treatments can increase CCKBR availability for antibody detection

• Observed vs. theoretical molecular weights:

  • Calculated molecular weight: 56 kDa

  • Observed weights: 64 kDa and 50 kDa on Western blots

  • This discrepancy is largely due to post-translational modifications

How can CCKBR antibodies be applied in G protein-coupled receptor research?

CCKBR antibodies provide valuable tools for studying this GPCR and its signaling pathways:

• GPCR classification studies:

  • CCKBR belongs to the family of G protein-coupled receptors

  • It mediates action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system

  • Antibodies help classify and understand GPCR family relationships

• Receptor-ligand interaction analysis:

  • CCKBR has high affinity for both sulfated and nonsulfated CCK analogs

  • Antibodies can help map binding domains through epitope blocking studies

• Drug development applications:

  • CCKBR is one of 157 GPCRs identified as targets for approved drugs

  • Antibodies facilitate screening of new compounds targeting this receptor

• Signaling pathway investigations:

  • CCKBR antibodies can be used to study downstream effects after receptor activation

  • They help identify key components in signaling cascades through co-immunoprecipitation studies

• Receptor trafficking studies:

  • Antibodies targeting different epitopes (extracellular vs. intracellular) can track receptor internalization

  • This helps understand receptor regulation and recycling

What experimental considerations are important when using CCKBR antibodies to study anxiety and pain mechanisms?

CCKBR plays critical roles in anxiety and pain processing, and antibodies targeting this receptor require special considerations:

• Sex-specific differences:

  • CCKBR involvement in pain and anxiety shows sex-specific patterns

  • Female subjects may show more prominent effects in certain models

  • Studies should include both sexes and analyze results separately

• Behavioral assessment selection:

  • Anxiety-like behavior: Light/dark box test is recommended

  • Depression-related assessments: Sucrose splash test shows good sensitivity

  • Pain measures: Von Frey testing for mechanical sensitivity

  • Memory/learning: Novel object recognition test

• Pharmacological interactions:

  • CCKBR antagonists enhance morphine analgesia and prevent/reverse tolerance

  • Consider interactions when designing studies involving both systems

  • Control for effects of compounds like proglumide that potentiate morphine and endogenous opiates

• Pain model selection:

  • CCKBR antibodies are particularly useful in neuropathic pain models

  • Foramen rotundum inflammatory compression trigeminal infraorbital nerve (FRICT-ION) model shows good sensitivity

  • Consider both reflexive and non-reflexive behavioral assessments for comprehensive evaluation

• Neuronal activity measurement:

  • Combine CCKBR antibodies with calcium imaging (GCaMP6s) to correlate receptor expression with activity patterns

  • In trigeminal ganglia cultures, CCKBR blocking reduces neuronal firing frequency

  • Digital recording of behavioral assays allows for detailed post hoc computer analysis