A protein (mCLCA1) has been cloned from a mouse lung cDNA library that bears strong sequence homology with the recently described bovine tracheal, Ca 2؉ -sensitive chloride channel protein (bCLCA1), bovine lung endothelial cell adhesion molecule-1 (Lu-ECAM-1), and the human intestinal Ca 2؉ -sensitive chloride channel protein (hCLCA1). In vitro, its 3.1-kilobase message translates into a 100-kDa protein that can be glycosylated

The tissue and cellular expression pattern of a recently cloned murine calcium-sensitive chloride channel (mCaCC) was determined. In situ hybridization was performed on formalin-fixed, paraffin-embedded murine tissues using digoxigenin-labeled, single-stranded RNA probes. The data were substantiated with northern blot and reverse transcriptase-polymerase chain reaction analyses. All three assays consistently indicated strong expression in tissues with secretory or ion regulatory functions, such as mammary gland, respiratory and intestinal epithelia, gall bladder, pancreas, kidney, uterus, and epididymis. Additional mCaCC expression was observed in germinal centers of lymphatic tissues, in spermatids, and in keratinocytes of the skin, esophagus, and cornea. The results are in accordance with previous electrophysiological reports on calcium-activated chloride conductances in various murine exocrine secretory epithelia and suggest a role of mCaCC in transepithelial ion transport. However, expression in other than secretory tissues indicates a more complex function.

A member of the cytochrome P450 superfamily has been identified within region 2D of the Drosophila X chromosome. The sequence of this gene shows strongest homology with P450 family 4 genes, and has thus been named CYP4D1 in accordance with convention. This P450 gene is expressed throughout Drosophila development, with the highest levels of transcript accumulation occurring during late larval stages. A fragment of Drosophila genomic DNA including the CYP4D1 gene has been reintroduced into the germ line by P-element-mediated transformation. This transduced fragment does not rescue any of the lethal mutations that have been identified in this genetically well-characterized region of the Drosophila genome.

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