Calbindin is a calcium-binding protein belonging to the troponin C superfamily .It is primarily expressed in certain
subtypes of neurons
NCBI Summary:
Calbindin 2 (calretinin), closely related to calbindin 1, is an intracellular calcium-binding protein belonging to the troponin C superfamily. Calbindin 1 is known to be involved in the vitamin-D-dependent calcium absorption through intestinal and renal epithelia, while the function of neuronal calbindin 1 and calbindin 2 is poorly understood. The sequence of the calbindin 2 cDNA reveals an open reading frame of 271 codons coding for a protein of 31,520 Da, and shares 58% identical residues with human calbindin 1. Calbindin 2 contains five presumably active and one presumably inactive calcium-binding domains. Comparison with the partial sequences available for chick and guinea pig calbindin 2 reveals that the protein is highly conserved in evolution. The calbindin 2 message was detected in the brain, while absent from heart muscle, kidney, liver, lung, spleen, stomach and thyroid gland. There are two additional forms of alternatively spliced calbindin 2 mRNAs encoding C-terminally truncated proteins. Exon 7 can splice to exon 9, resulting in a frame shift and a translational stop at the second codon of exon 9, and encoding calretinin-20k. Exon 7 can also splice to exon 10, resulting in a frame shift and a translational stop at codon 15 of exon 10, and encoding calretinin-22k. The truncated proteins are able to bind calcium.
Cao QJ, et al 2001 reported the expression of calretinin in human ovary, testis, and ovarian
sex cord-stromal tumors.
Calretinin, a calcium-binding protein, is primarily expressed in certain
subtypes of neurons. It has also been found to be present in mesothelial cells
and mesotheliomas but not in many types of carcinomas. Using a polyclonal
anti-calretinin antibody, the authors investigated the expression of calretinin
immunohistochemically in nonneoplastic human ovaries and testes and ovarian
sex cord-stromal tumors (SCSTs). In ovaries, calretinin was expressed in theca
interna cells, hilus cells, and scattered individual stromal cells. Oocytes,
granulosa cells, theca externa cells, rete ovarii, and most stromal cells were
negative. Expression of calretinin was also seen in the ovarian surface
epithelium and in collapsed and flat epithelial inclusion glands (EIGs), but
not in round, columnar, and ciliated EIGs.
Follicle stages
Comment
Movahedi-Lankarani S, et al 2002 reported that calretinin is a more sensitive but less specific marker than
alpha-inhibin for ovarian sex cord-stromal neoplasms.