title: Molecular characterisation of the smooth endoplasmic reticulum Ca(2+)-ATPase of Porcellio scaber and its expression in sternal epithelia during the moult cycle.
abstract: The anterior sternal epithelial cells of the terrestrial isopod Porcellio scaber transport large amounts of calcium during the formation and resorption of intermittent calcium carbonate deposits. Recent investigations on epithelia involved in mineralisation processes suggest a role of the smooth endoplasmic reticulum Ca(2+)-ATPase (SERCA) in transcellular calcium transport. We present the first molecular characterisation of a SERCA within a crustacean mineralising epithelium. We cloned the SERCA from a cDNA library of the anterior sternal epithelium and used in situ hybridisation to compare the expression of the SERCA mRNA between three different moulting stages. The full-length SERCA cDNA has an open reading frame of 3006 nucleotides. The deduced 1002 amino-acid polypeptide has a predicted molecular mass of 109.7 kDa and 87% identity to the SERCA of Procambarus clarkii axial muscle isoform. In situ hybridisation confirmed expression within the anterior sternal epithelium and revealed an increase in SERCA mRNA abundance from the non-transporting, early premoult stage to the calcium transporting, late premoult and intramoult stage. The results support previous indications of a contribution by the smooth endoplasmic reticulum to transcellular calcium transport and suggest a transcriptional regulation of SERCA activity.
authors.affiliation: Z.E. Elektronenmikroskopie, Universität Ulm, 89096 Ulm, Germany.
authors.forename: Monica
authors.initials: M
authors.lastname: Hagedorn
authors.forename: Dirk
authors.initials: D
authors.lastname: Weihrauch
authors.forename: David W
authors.initials: DW
authors.lastname: Towle
authors.forename: Andreas
authors.initials: A
authors.lastname: Ziegler
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D000252:Calcium-Transporting ATPases / Q000235:genetics*; D017931:DNA Primers; D018871:Endoplasmic Reticulum, Smooth / Q000235:genetics*; D004848:Epithelium / Q000201:enzymology; D020869:Gene Expression Profiling; D057927:Hydrophobic and Hydrophilic Interactions; D017403:In Situ Hybridization; D033321:Isopoda / Q000201:enzymology* / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D017931:DNA Primers; D000252:Calcium-Transporting ATPases