What Makes an Anti-Rat Calretinin Polyclonal Antibody Useful?
The anti-Rat Calretinin Polyclonal Antibody (CALB2, catalog number MBS502148) is a research-grade immunoreagent produced in sheep against the calretinin protein expressed in rat tissue. Calretinin is a 29 kDa intracellular calcium-binding protein encoded by the CALB2 gene, primarily expressed in distinct subpopulations of neurons and in mesothelial cells. Because of its selective distribution, high-quality anti-calretinin antibodies serve as powerful tools for identifying neuronal subtypes, tracing circuit elements, and distinguishing malignant mesothelial cell lineages in tissue pathology research.
Why Target Calretinin in Research?
Calretinin occupies a unique position among calcium-binding proteins because of both its selective expression pattern and its functional significance. Within the mammalian brain, calretinin selectively marks a subset of GABAergic interneurons — neurons that use gamma-aminobutyric acid (GABA) as an inhibitory neurotransmitter. These calretinin-positive interneurons represent a functionally and morphologically distinct population from parvalbumin- and calbindin-positive interneurons, and they participate in specific microcircuit functions including disinhibition and modulation of principal cell excitability.
In the context of disease research, calretinin is studied because this neuronal population shows selective vulnerability in conditions including epilepsy, Alzheimer’s disease, schizophrenia, and ischemic injury. Quantifying calretinin-immunoreactive neuron density in animal models provides a sensitive readout of interneuron integrity and circuit-level pathology.
Polyclonal vs. Monoclonal Antibodies for Calretinin Detection
Polyclonal antibodies against calretinin are generated by immunizing an animal host with the target antigen, resulting in a mixture of antibodies recognizing multiple epitopes across the calretinin protein. This multi-epitope recognition provides several practical advantages:
- Higher sensitivity — multiple antibody clones bind simultaneously, amplifying the signal
- Robustness — if one epitope is masked by fixation or sample conditions, other epitopes remain accessible
- Versatility — a single polyclonal antibody often performs across multiple applications including WB, IHC, and IF
Monoclonal antibodies, by contrast, recognize a single epitope and offer superior specificity for applications requiring minimal cross-reactivity. The choice between monoclonal and polyclonal depends on the application, sample conditions, and level of background acceptable for the experiment.
Validated Applications of the Anti-Rat Calretinin Polyclonal Antibody
Western Blot (WB)
In Western blot applications, the anti-rat calretinin polyclonal antibody detects a specific band at approximately 29 kDa in rat brain lysates — consistent with the expected molecular weight of calretinin. This application is particularly useful for comparing CALB2 expression levels across brain regions, developmental time points, or experimental conditions. Standard dilution optimization is recommended to achieve the optimal signal-to-background ratio for each laboratory’s specific SDS-PAGE and transfer conditions.
Immunohistochemistry (IHC)
The antibody is validated for use in immunohistochemistry on formalin-fixed, paraffin-embedded (FFPE) or paraformaldehyde-fixed tissue sections. In rat brain tissue, calretinin-immunoreactive neurons can be visualized in the cortex, hippocampus, cerebellum, olfactory bulb, and spinal cord, corresponding to the established distribution of calretinin-positive interneurons in the rat nervous system. Antigen retrieval — typically achieved by heat-induced epitope retrieval in citrate or EDTA buffer — may be required for optimal staining in FFPE sections.
Immunofluorescence (IF)
In immunofluorescence applications, the anti-rat calretinin antibody enables visualization of calretinin protein localization in cultured rat neurons, cell lines, or brain slice preparations. Co-staining with antibodies against other neuronal markers — such as NeuN, GABA, or parvalbumin — allows researchers to phenotypically characterize calretinin-positive interneurons and assess their spatial relationships within neural circuits.
Cross-Reactivity and Species Considerations
The anti-rat calretinin polyclonal antibody (MBS502148) is produced against rat calretinin and validated specifically for rat samples. Based on the high degree of sequence conservation between rat, human, and mouse CALB2 proteins — which share significant amino acid identity — cross-reactivity with human and mouse tissue is expected, though independent validation is recommended when using the antibody with non-rat samples for the first time. A cross-absorption step against the alternative species tissue may be performed if background from cross-reacting proteins is observed.
Conclusion
The anti-Rat Calretinin Polyclonal Antibody (MBS502148) is a well-characterized research reagent for studying calretinin biology in the rat model system. Validated across Western blot, immunohistochemistry, and immunofluorescence, it supports a broad range of research programs in neuroscience, developmental biology, and oncology. Access this antibody alongside a comprehensive catalog of neuronal marker antibodies and supporting reagents at MyBioSource.
