Porta AR ; Bettini E ; Buiakova OI ; Baker H ; Danho W ; Margolis FL ;

Brain Res Mol Brain Res vol. 41 (1-2)   pp. 81-9, 5 Sep 1996

Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110-1199, USA.

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 protein. 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.

Amino acid sequence ;  Animal ;  Base Sequence ;  Calcium: metabolism ;  Calcium-Binding Proteins: chemistry: genetics: isolation & purification ;  Chemoreceptors: metabolism ;  Cloning,Molecular ;  DNA,Complementary: genetics ;  Epidermis: metabolism ;  Gills: metabolism ;  Ictaluridae: genetics: metabolism ;  In situ hybridization ;  Molecular Sequence Data ;  Multigene Family ;  Nerve Tissue Proteins: metabolism ;  Olfactory Pathways: metabolism ;  Organ Specificity ;  Protein Conformation ;  RNA,Messenger: analysis ;  Recombinant Fusion Proteins: metabolism ;  Support,U.S.Gov't,P.H.S. ;  Transcription Factors: chemistry: genetics: isolation & purification ;  26740 ;