Disease relevance of CALB2

• The calretinin gene was expressed in Escherichia coli and produced immunoreactive calretinin of the expected size [1].
• In the cat ganglion cell layer, the calretinin antisera define a new, asymmetric, type of cell [2].

Psychiatry related information on CALB2

• Thus, CR mRNA and protein appear to be constitutively expressed in NM neurons and are not affected by sensory deprivation [3].

High impact information on CALB2

• Calretinin and calbindin are expressed in different sets of neurons throughout the brain [4].
• The amino acid sequence of fragments from proteolytic digestion of protein 10 revealed an 86% sequence identity with a calcium-binding protein (calretinin) found in chicken retina [5].
• Sequence analysis identifies six EF-hand calcium-binding domains and reveals 42% and 37% homology to chicken calretinin and calbindin D-28k, respectively [6].
• The neurons derived from NPE cells express neurofilament, beta3 tubulin, RA4, calretinin, Islet1, or Hu, and a few produced long axonal projections, several millimeters in length that extend across the ciliary body [7].
• Calretinin immunoreactivity in pineal gland of different mammals including man [8].

Biological context of CALB2

• Calretinin is a member of the EF-hand calcium-binding protein family, with a high similarity with calbindin D28k [1].
• The chick calretinin cDNA sequence was reconstructed in a M13 vector and transferred into an expression plasmid derived from the pET series [1].
• The introns are in the same positions in the calretinin and calbindin genes [9].
• The sequence of the calretinin cDNA revealed an open reading frame of 271 codons coding for a protein of 31,520 Da, and sharing 58% identical residues with human calbindin D28k [10].
• With development, calretinin immunoreactivity expanded from nucleus to cytoplasm, and calretinin immuno-positive cell number increased [11].

Anatomical context of CALB2

• Calretinin immunoreactivity presented a peak (both in number of cells and in intensity) at E15 and fell dramatically after E20 while calbindin immunoreactivity was restricted to the Purkinje cells and increased with the development of these cells [12].
• The antisera have been used in an immunohistochemical survey of calretinin and calbindin in the chick sensory nuclei and ganglia, where these two proteins are found to be particularly prevalent [13].
• In chicken dorsal root ganglia, calretinin immunoreactivity is expressed by a subpopulation of large A-neurons, most of which co-express calbindin D-28k [14].
• Calretinin and calbindin-D28k are two calcium-binding proteins that are present in largely different sets of nerve cells in the central nervous system [15].
• There is also an early phase of calbindin immunoreactivity in many immature amacrine cells, and of calretinin immunoreactivity in the presumptive photoreceptor layer, suggesting that these proteins may have distinct functions in differentiating cells [15].

Associations of CALB2 with chemical compounds

• Bacterially expressed calretinin was purified with successive ammonium-sulfate precipitation, DEAE chromatography, hydroxyapatite chromatography, Sephadex G-75 chromatography and Mono-Q chromatography [1].
• Weak gamma-aminobutyric acid (GABA) immunoreactivity was observed only in a few of the trkA-IR horizontal cells, whereas the overlap of calretinin and GABA immunoreactivities was 100% [16].
• We found that the large glucagon-expressing neurons were immunoreactive for substance P, neurofilament, Pax6, AP2alpha, HuD, calretinin, trkB, and trkC [17].
• Comparison between the lack of calmodulin and the presence of calretinin, belonging to the same calcium-binding protein family, in chick pinealocytes raises the hypothesis about a possible role of calretinin in melatonin synthesis [18].

Regulatory relationships of CALB2

• The number of calretinin-expressing cells that were generated was increased approximately 20-fold with forced expression of NeuroD [19].
• Similar to the bullwhip cells, the conventional glucagon-expressing amacrine cells were immunoreactive for calretinin, HuD, Pax6, and AP2alpha [17].

Other interactions of CALB2

• We identified horizontal cells by indirect immunofluorescence with antibodies to calretinin, trkA, GABA, Prox1, AP2alpha, Pax6, islet1, and Lim1 + 2 [16].
• NeuroD induces the expression of visinin and calretinin by proliferating cells derived from toxin-damaged chicken retina [19].
• Many cells transfected with the NeuroD-virus expressed calretinin, neurofilament, or visinin, while most cells remained undifferentiated [19].
• Parvalbumin and calretinin in the avian thymus [20].
• Most of the newly formed cells remain undifferentiated, expressing Pax6 and Chx10, whereas some differentiate into Müller glia, and a few differentiate into neurons that express the neuronal markers Hu or calretinin [21].

Analytical, diagnostic and therapeutic context of CALB2

• The distribution of calretinin and calbindin mRNAs in chick tissues has been mapped using RNA gel blots and in situ hybridization [4].
• To contribute to the knowledge of the presence of CR-positive cells in the pineal parenchyma of rat and other mammalian including man, we performed immunocytochemistry on pineal glands of gerbils, rats, goats, cows, and humans, using a CR anti-serum [8].
• To confirm it was actually CR that was demonstrated, we performed Western Blot analyses [8].
• Ischaemia for 45 min causes a change in the nature of the normal calretinin immunoreactivity, an obliteration of the ChAT immunoreactivity and a drastic reduction in the b-wave of the electroretinogram after 3 days of reperfusion [22].
• Native calretinin was purified from chick brainstem using the same method as for the recombinant protein but with an added affinity chromatography step [23].

References