Molecular cloning of ictacalcin: a novel calcium-binding protein from the channel catfish, Ictalurus punctatus

• Published in: Brain research. Molecular brain research. 1996-09, Vol.41 (1), p.81-89
• Main Authors: Porta, Angela R, Bettini, Ezio, Buiakova, Olesia I, Baker, Harriet, Danho, Waleed, Margolis, Frank L
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Calcium - metabolism; Calcium-binding protein; Calcium-Binding Proteins - chemistry; Calcium-Binding Proteins - genetics; Calcium-Binding Proteins - isolation & purification; cDNA library; Chemoreceptor Cells - metabolism; Cloning, Molecular; DNA, Complementary - genetics; Epidermis - metabolism; Fundamental and applied biological sciences. Psychology; Gills - metabolism; Ictaluridae - genetics; Ictaluridae - metabolism; In Situ Hybridization; Metabolisms and neurohumoral controls; Molecular Sequence Data; Multigene Family; Nerve Tissue Proteins - metabolism; Nitrogen metabolism. Proteins. Glycoproteins. Nucleic acids. Collagen; Nucleotide sequence; Olfactory Pathways - metabolism; Olfactory tissue; Organ Specificity; Protein Conformation; Receptors, Cell Surface; Recombinant Fusion Proteins - metabolism; RNA, Messenger - analysis; S100; Teleost; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - isolation & purification; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0169-328X; 1872-6941
• DOI: 10.1016/0169-328X(96)00069-1

Calcium is essential for a variety of functions in animals, including signal transduction, transmission of nerve impulses, and bone and scale growth. In freshwater adapted teleosts, blood calcium levels are maintained constant (2–4 mM) even at low external calcium concentration (< 0.01 mM). Epithelial cells in skin and gill have been implicated in calcium homeostasis. We have cloned a cDNA from Ictalurus punctatus, the channel catfish, that codes for ictacalcin, a novel member of the S100 family of calcium-binding proteins. In-situ hybridization demonstrates ictacalcin mRNA is abundant in epithelial cells of olfactory rosette, barbel, skin and gill but not brain or muscle. The presence of ictacalcin protein in these tissues was confirmed by immuno-blot analysis. Tissue extracts and recombinant ictacalcin bind calcium with attendant changes in electrophoretic mobility indicative of changes in protein conformation. The calcium-binding activity and abundant localization of ictacalcin in epithelial cells of several tissues indicates that this protein plays an important role in catfish calcium homeostasis.