Mouse Monoclonal Antibody to Calretinin Cat# MCA-3G9

      Calretinin, as the name suggests, was originally isolated in the retina but was found to be also expressed in mammalian central nerve system, testis, fallopian tube and pancreas (1). It is a cytoplasmic Calcium binding protein which includes typical “EF hand" structures the prototype for which is the protein parvalbumin (2-4). In the brain calretinin it is localized in certain classes of neurons, and antibodies to it are useful for identifying specific neuronal cell types (1). It is particularly concentrated in some cerebellar granular cells and their parallel fibres, but is also found in many GABAergic interneurons in the cortex. These GABAergic interneurons in most cases express only one of three related Calcium binding proteins, namely calretinin, calbindin or parvalbumin (5,6). As a result these important inhibitory interneurons can be identified and classified based on their content of these three proteins. Each type of neuron as defined in this fashion has distinct electrophysiological and functional properties (7). Calretinin deficiency in the mossy cells of the mouse dentate gyrus and granule cells results in abnormal excitability in the cerebellar neuronal network and impairment of long-term potentiation and motor coordination, suggesting that calretinin functions as a general Calcium buffer (8).

Chromogenic immunostaining of a 4% PFA fixed paraffin embedded rat cerebellum section with mouse mAb to parvalbumin, MCA-3C9, dilution 1:2,000, detected in DAB (brown) using the Vector Labs ImmPRESS method and reagents with citra buffer retrieval. Hematoxylin (blue) was used as the counterstain. In the cerebellum, MCA-3C9 antibody strongly labels Purkinje cells, basket cells and Golgi cells. This antibody performs well in testing with 4% PFA or standard NBF fixed rat and human tissues. Mouse select image for larger view.



Immunofluorescent analysis of rat brain cerebellum section stained with mouse mAb to parvalbumin, MCA-3C9, dilution 1:1,000, in green, and costained with chicken pAb to calbindin, CPCA-Calb, dilution 1:2,000 in red. Following transcardial perfusion of rat with 4% paraformaldehyde, brain was post fixed for 24 hours, cut to 45μM, and free-floating sections were stained with above antibodies. Most Purkinje cells coexpress parvalbumin and calbindin and so appear yellow, whereas basket, stellate and Golgi cells express parvalbumin only and so appear green. Mouse select image for larger view.

1. Rogers JH. Calretinin: a gene for a novel calcium-binding protein expressed principally in neurons. J. Cell Biol. 105:1343-53 (1987).
2. Kretsinger RH, Nockolds CE. Carp Muscle Calcium-binding Protein: II. Structure determination and general description. J. Biol. Chem. 248:3313-26 (1973).
3. Andressen C, Bliimcke I, Celio MR. Calcium-binding proteins: selective markers of nerve cells. Cell Tissue Res. 271:181-208 (1993).
4. Schwaller B, Meyer M, Schiffmann S. ‘New’ functions for ‘old’ proteins: The role of the calcium binding proteins calbindin D-28k, calretinin and parvalbumin, in cerebellar physiology. Studies with knockout mice. The Cerebellum 1:241–58 (2002).
5. Condé F, et al. Local circuit neurons immunoreactive for calretinin, calbindin D‐28k or parvalbumin in monkey prefronatal cortex: Distribution and morphology. J. Comp. Neurol. 341:95-116 (1994).
6. Hof PR, et al. Cellular distribution of the calcium-binding proteins parvalbumin, calbindin, and calretinin in the neocortex of mammals: phylogenetic and developmental patterns. J. Chem. Neuroanat. 16:77-116 (1999).
7. Bearzatto B, et al. Mono- and dual-frequency fast cerebellar oscillation in mice lacking parvalbumin and/or calbindin D-28k. Eur. J. Neurosci. 22:861-70 (2005).
8. Schiffmann SN, et al. Impaired motor coordination and Purkinje cell excitability in mice lacking calretinin. PNAS 27:5257-62 (1999).