The calcium-binding protein calretinin-22k, an alternative splicing product of the calretinin gene is expressed in several colon adeno carcinoma cell lines.
An alternatively spliced mRNA for the calcium-binding protein calretinin (CR) is present in the colon adenocarcinoma cell line WiDr. As a consequence of a frame shift, the resulting protein, calretinin-22k (CR-22k), consists of the first 178 amino acids of calretinin followed by a carboxy-terminal peptide of 14 amino acids that is not present in full-length calretinin. Antibodies specific for this C-terminal region have been generated by 2 different methods. A peptide corresponding to the specific C-terminal region of CR-22k was either chemically synthesized and coupled to a carrier protein or was expressed in Escherichia coli as a carboxyterminal fusion to a carrier protein applying recombinant techniques. Both antisera produced in rabbits were tested in Western blots and immuno-histochemical experiments. The antisera recognized human recombinant CR-22k overexpressed in E. coli, but not fulllength calretinin and stained fixed WiDr cells. The presence of CR-22k was also confirmed in the colon cell lines CO115/3 in which mRNA coding for CR-22k mRNA coding for CR-22k mRNA is present as well as in the lines COLO205 and LS-180, all of which also express full-length calretinin. Although the intracellular distribution of CR-22k and CR are similar as evidenced by immunohistochemical stainings, CR-22k is preferentially localized in the nucleus in the cell lines LS-180 and Co115/3 suggesting potentially different roles for the two proteins.
Gander
J C
JC
Institute of Histology and General Embryology, University of Fribourg, Switzerland.
Bustos-Castillo
M
M
Stüber
D
D
Hunziker
W
W
Celio
M
M
Schwaller
B
B
D000230:Adenocarcinoma / Q000473:pathology*; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000096:biosynthesis / Q000276:immunology / Q000302:isolation & purification; D001483:Base Sequence; D015153:Blotting, Western; D064032:Calbindin 2; D003110:Colonic Neoplasms / Q000473:pathology*; D000939:Epitopes / Q000276:immunology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D064030:S100 Calcium Binding Protein G / Q000235:genetics*; D014407:Tumor Cells, Cultured
D000951:Antigens, Neoplasm; C576764:CALB2 protein, human; D064032:Calbindin 2; D000939:Epitopes; D064030:S100 Calcium Binding Protein G